Girl I like is dating my best friend

Hey I hope someone can help. Basically my best mate is dating his neighbour - however, i have been talking to her for about 3 months and i really like her (they have been dating for about a month). I know I really like her and she repeatedly told me she had a crush on me back in december and I did aswell however I didn't want to make anything awkward between her and my best mate seeing as we met through him. Then I finally got up the courage to ask her out before New years but then I got covid - completely ruined everything. I then stopped myself and was gonna assk her once I got back to school. However, after school on my first day back after isolation, I found out he had literally asked her out that day. I was kinda heartbroken to hear this as I still really like her and we still talk - however whenever she is with him; obvs because they are neighbours it is quite a lot, her texts turn really dry like she can't be bothered.
I don't know if this is him making her do it as he did it when he was dating his ex back last summer with another one of our mates. But it seems like whenever she isn't with him she opens back up again. She openly admitted to me less that 3 days ago that she liked me and the only reason she didn't anymore was "it grew less because we grew more distant" however that was just because he made me stop texting her for a bit (like a day or 2 whilst I had covid). Essentially he screwed me there.
We also had the convo before they started dating if he liked her and he said "na bro she's like a sister to me" and I know she likes him but apparently she doesn't feel he likes her back that much and he isn't known for having relationships that last as he isn't romantic and doesn't really care abt the small things that makes girls feel special.
I don't know what to do, whether to just leave it and see what happens with time - I doubt they will last too long tbh but then I have the issue with she just dated my best mate, can I date her or is that harsh on him? Or is it just strange?
Or I can sort of just tell him that I like her but I don't know if that will end well or I can stop talking to her - which I have tried like leaving her on delivered but I simply can't do it for long because I like her too much.
Does anyone have any advice

(it is my post) here is some more info
Basically I know she tells me stuff she doesn't necessarily tell him and I like to be there for her and stuff and idk if it is just better off if we stay friends and I try to move on (it'll be hard) and then we can stay friends but like rly close. I just can't tell how it would work because currently we do have kind of flirty texts if you know what I mean, like not proper flirt but we are both there for each other and we tell each other so much and like stuff we won't tell anyone else and I just don't know how it will change if we start dating and stuff and I know she rly appreciates me and I have told her and I do respond if she needs my advice or help and I always tell her im there for her which I don't think her bf does so I just don't know whether I am kind of like the 2nd boyfriend just without the physical side and stuff but like the emotional bf yk. But even then I feel like if he saw some of our messages he would not be happy because we r so close and he doesn't do half the stuff I do when talking to her.

I don't see a way you can come out of this without losing the friend or the girl.
You either have to wait it out until they break up and risk her becoming distant or just fess up now. Who knows, she might still have that crush on you and her admitting she had a crush before was just a subtle hint.
If you do wait it out, I guess there'll be less hostility between you and your friend, but it still feels weird to be dating your best friend's ex.

you have to ask yourself
who would you rather lose? Your best mate or your crush? I dont see a scenario where you could keep both your connections tbf

I can't actually tell. Cause she told me she didn't like me like that but then she said she had a crush on me which I already knew only a few days later. So I can't tell. The thing is if I try anything now then I can lose both of them (she knows I still like her cause we had the convo the other day that's when she brought it up). I don't want to come between them but I do rly like her and it does rly frustrate me when she just doesn't respond which is probably a sign of how much I like her yk. But here the thing all of my other mates think I'm a better fit for her and that I'm better looking and an overall nicer person than my best mate. And I have to stand there and take it but I can't show that I like her to too many ppl. He also asked me straight up if I liked her and I literally panicked and said yeh before u started dating her. He was like ok. But tbh she doesn't seem to trust him - and in schl and stuff when he isn't around her he is always flirting with girls.
it's just annoying waiting to see what happens and I think she is too scared to break up with him because she is worried it'll be awkward because they go to schl together everyday on the bus and stuff. I just honestly can't tell what to do whether to wait or not.
She knows I like her currently so ig the issue is that I can't tell my mate anything abt it and she won't do anything abt it.
I'm gonna end up waiting cause if I break them up then I loose both ways but if they break up and I'm there for her and stuff maybe she will see me properly as an option ygm

If she already knows you like her, then really all you are waiting for is for her to decide between you two.
There's no point in messing up your relationship with your friend over a girl who might not choose you.
Besides if he's flirting with other girls, this relationship doesn't look like it's going to last long and it might be her last push to break up with him.
But tbh, If she really liked you, I think she would have risked the awkwardness to be with you. I think you should wait.

Yeh ig, tbh she knows I like her I just honestly can't tell how serious they are abt each other and stuff. The rly annoying part is he Yeh ig, tbh she knows I like her I just honestly can't tell how serious they are abt each other and stuff. The rly annoying part is he only flirts when she isn't there - if she is there he goes off and plays football or goes over to her and her friends. He flirts with at least 4 girls in form everyday and its not in a friendly way its properly and stuff and then he flirts with other girls in lessons and stuff. But tbh as soon as anyone that can tell her appears he stops and tries to hide it. From my POV their relationship just seems convenient to him because he gets a girl he can hang out with almost whenever cause they are neighbours and he just doesn't need to try necessarily. I think he knows that she won't break up with him either because of how close their families are and stuff and I just feel it's not actually what she wants and she just can't get out of it.
She messaged me a few mins ago literally asking if I know if he is mad at her and I was like I honestly have no clue because I don't. He doesn't always seem to be in her good books either when I see him he is always like "why are you mad at me" and stuff.
She is having a party in a few weeks and there is a massive gc with us 2 and one of our other friends and all of her friends cause its her party. And whenever one of her friends texts on the gc he is always like flirting with them and I don't understand how she doesn't see it. She has come to me before to ask if I have noticed it and I obvs said I had and I have even tried to stop it before when he did it but he doesn't seem to notice it at all and just does it anyway.
From my view I see this relationship crashing at somepoint but I dont know when and im getting a bit frustrated abt waiting. We have GCSEs in 3 months and if it happens any other point other than the next month im not gonna make a move so I can focus and then I hope she will still be single at the end of the GCSEs so we can have a summer together and stuff.
Its just a rly slow and annoying situation ig

If she's constantly having to ask if they are okay then there should be some alarm bells ringing in her head and she's just choosing to ignore it. As I said, the best thing you can do is wait and just focus on your exam. You should just let them work it out between themselves before adding yourself to the equation. The last thing you need is some next-level drama right before your GCSEs. Continue being her friend and act normal, it's probably hard seeing the girl you want be with someone else but there is literally nothing you can do without making things blow up in your face.
You are going to go off to college/sixth form and lose touch with most of these people anywayz. Even her. If you don't end up at the same school then it's unlikely to work out. Who knows, maybe you'll even find someone better in sixth form.