Partner is an escort

she would probably choose him over you, given the chance, which is why it bothers you so much. the good news is, someone in his position would never settle for a sex worker. she's just a fantasy to him that he can switch on and off.

As harsh as that feels I do get it. Just fyi we are married, we are all in on everything. But yes I think there is that doubt of like, if I make a wrong move or are not on my game to be the best most of the time that he's like waiting in the shadows for her to fall on too as a security blanket and then I'm just in the dust...it makes me so frustrated that it's legit just this 1 guy who tbh I'm not trying to ego challenge him but I am younger buy 35+ years and much better looking and friends and family dynamics is better but like, I work soooo fkn hard to be successful and I don't think I'll ever get to his level on that and that I feel is what makes me insecure cos he can give anything and everything in a second. I mean he buys her expensive gifts that like yeh I can afford but my mind set is I put that money into paying off our home faster. But like he can do both like chump change, so I just worry he might try "buy" her love in a way. She isn't a materialistic as some may think but she does love those types of things.
I don't know if I should fully open up about this too her, and risk her then saying ill stop seeing him but then resenting me because I stopped a big source of income for her and us and then I've pretty much fked it all myself.

most people like that aren't self-made so i would try not to feel too bad. 99.99% of the time that sort of money is generational wealth.
if you tell her all this, it will probably make you look weak and insecure, which just isn't attractive. it will also be hypocritical. at least that's how i'd see it: 'so you let me do it with all the others but not with him just because you know he's better than you'? - like this would be my train of thought. but idk, it's up to you

Being practical for a minute, is she allowed to do this on a study visa? Are your finances likely to be checked if applying for any kind of business loan etc?
Was she an escort before you married? Why can't she get another job? For how long will she be doing before you start working together?

It's legal in my country, it's all legitimate. She was doing it prior, she can't get another job right now that's as flexible that earns the money she needs and what we need for our goals.

The best way to conquer your jealousy is to use all the natural empathy that you have for your wife. To see things from her point of view. And then to use the logical half of your brain to work out what's best for her now and going forwards.
She should drop all of her clients apart from this rich guy. Whom she should continue to see. And maybe even strengthen the bonds with. She should milk him for as much money as she can, and continue to milk him. Whilst also enjoying his company as much as she can.
Your logic should also tell you that divorcing you may be or may become in the future a better option for her than staying married to you.
In the event of you divorcing, she'll be OK and you'll be OK.
Does the millionaire client know she's married? And know she's married to you?
It's possible that what he's in love with is somewhat of an illusion as to the real her, and that as he gets to know her and the honeymoon period wears off, he'll flip from loving your wife to hating her.
A large part of you should be genuinely delighted that she's earning so much money from him in such an easy and pleasant way from her point of view. That's what you should focus on. The positives. And not the negatives of your naturally jealous emotions.
There's the lover vs provider frame. It's great that you're highly motivated to make a financial success of your life. Great for you, regardless of any relationships, and great for your wife.
However, you should aim to primarily place yourself in the lover frame with your wife. As long as you continue to display large amounts of mental and emotional strength, she will be attracted to you. As long as you also go on enough adventures and mini-adventures (most of which can be free or inexpensive) with her, you will be able to maintain the spark.
The millionaire punter can out-provide you. Don't compete on that. Compete on you out-lovering him. With this being something where you can blow him out the water, week after week, month after month.

The best way to conquer your jealousy is to use all the natural empathy that you have for your wife. To see things from her point of view. And then to use the logical half of your brain to work out what's best for her now and going forwards.
She should drop all of her clients apart from this rich guy. Whom she should continue to see. And maybe even strengthen the bonds with. She should milk him for as much money as she can, and continue to milk him. Whilst also enjoying his company as much as she can.
Your logic should also tell you that divorcing you may be or may become in the future a better option for her than staying married to you.
In the event of you divorcing, she'll be OK and you'll be OK.
Does the millionaire client know she's married? And know she's married to you?
It's possible that what he's in love with is somewhat of an illusion as to the real her, and that as he gets to know her and the honeymoon period wears off, he'll flip from loving your wife to hating her.
A large part of you should be genuinely delighted that she's earning so much money from him in such an easy and pleasant way from her point of view. That's what you should focus on. The positives. And not the negatives of your naturally jealous emotions.
There's the lover vs provider frame. It's great that you're highly motivated to make a financial success of your life. Great for you, regardless of any relationships, and great for your wife.
However, you should aim to primarily place yourself in the lover frame with your wife. As long as you continue to display large amounts of mental and emotional strength, she will be attracted to you. As long as you also go on enough adventures and mini-adventures (most of which can be free or inexpensive) with her, you will be able to maintain the spark.
The millionaire punter can out-provide you. Don't compete on that. Compete on you out-lovering him. With this being something where you can blow him out the water, week after week, month after month.

So currently she's with him now for last 3 days..man it's lonely AF... I think its because I over think the situation too much..like my thought process is so fkn stupid..
It's like
He gets her gifts
He takes her to amazing restaurants
He (recently) has more intimacy moments with her (I.e sex mainly) not saying that's why I'm with her but it still sucks
He's gets the fun parts of her never has to deal with the serious parts of the relationship
And with this guy she has to give more attention so her response times are like many hours apart, but she does the best she can, secretly face times me in the bathroom haha which I genuinely love and appreciate her doing that cos she knows its hard for me..
Just man, I try so hard to switch off and it's just this mfkr 🤣😅 i hate that my ego it's hurt by him..
I have gotten better tho in how I react to it but I'm still struggling internally...I just don't know if I'll break in a year or so and ask her just not to see this particular client anymore.. but I'd hate to stop her as that us not my decision nor should it be, I try my hardest to accept it like any other job and respect it fully..
Just hard when u have no one to vent too becuase obvious reasons, like normally guys can vent to mates or parents and girls to their girlfriends and u can discuss things without hurting ur partners feelings and help you get over things or see others perspectives, but this you really can't. But I am trying to like self reflect or discuss internally which sorta sounds crazy saying it out loud haha but I'm trying different avenues

But you've never said how long you expect this to continue. When will you have enough money for your business? A year? Two? Five?

So currently she's with him now for last 3 days..man it's lonely AF... I think its because I over think the situation too much..like my thought process is so fkn stupid..
It's like
He gets her gifts
He takes her to amazing restaurants
He (recently) has more intimacy moments with her (I.e sex mainly) not saying that's why I'm with her but it still sucks
He's gets the fun parts of her never has to deal with the serious parts of the relationship
And with this guy she has to give more attention so her response times are like many hours apart, but she does the best she can, secretly face times me in the bathroom haha which I genuinely love and appreciate her doing that cos she knows its hard for me..
Just man, I try so hard to switch off and it's just this mfkr 🤣😅 i hate that my ego it's hurt by him..
I have gotten better tho in how I react to it but I'm still struggling internally...I just don't know if I'll break in a year or so and ask her just not to see this particular client anymore.. but I'd hate to stop her as that us not my decision nor should it be, I try my hardest to accept it like any other job and respect it fully..
Just hard when u have no one to vent too becuase obvious reasons, like normally guys can vent to mates or parents and girls to their girlfriends and u can discuss things without hurting ur partners feelings and help you get over things or see others perspectives, but this you really can't. But I am trying to like self reflect or discuss internally which sorta sounds crazy saying it out loud haha but I'm trying different avenues

There's one huge advantage that you have over him.
He has to pay her large amounts of money for all this.
You don't have to pay her a single penny. And it's even possible that she's paying more into the household expenses than you are. So that she's saving you money, which kind of, in effect is her paying you to be with you.
And there will be a large element of her looking down on him, because he's paying her.
Serious parts of the relationship? What serious parts? You're in the lover frame. It's all lightness and joy and fun and adventures.

There's a significant proportion of billionaires that are less happy in their romantic relationship side of their lives than the average man in the street.
The sort that are in bickering relationships with their wives.
Have you sat down with your wife and worked out a budget?
IE looked at the take home pay of each of you. Compared that to the bills: mortgage, utility bills, commuting costs, car running costs, food, entertainment, holiday costs.
And then from there worked out how much free spending money each of you has and how much each of you could aim to put aside into investments.
Just looking at the figures and the reality of the situation may be useful.
You could work out what the impact on the budget would be if she was no longer getting money off the rich guy.
It's illogical for you to be fine with your wife going with average punters, but not with this rich punter. Because of the risks of infection, or the guy beating her up etc. Risks vs reward, from her point of view.
It's fine for you to have feelings on all this. What will differentiate you from the sort of guys your wife would not want to be married to, is how you behave in response to your emotions. So far, from what you've told us, you've been doing fine.
It's also worth reminding yourself, from time to time to not pedestalise your wife and to elevate her too high above you.
She has many qualities. However, she's an escort. And that alone makes her the sort of woman that most men wouldn't marry nor stay married to. And of the minority of men that would, most of them would be looking to control her by either trying to stop her or trying to maximise the income from her and grabbing that income off her. There's very few men that would be as tolerant as you over her escorting.
She's not daft. She will realise this. And realise what a diamond she has in you.