Pregnant by my old teaching assistant help

Is there any particular clear logical reason as to why abortion is not an option?
If there is, then what this teaching assistant wants and what he gets will be 2 very different things!
Because, as a bare minimum he will have some financial responsibility for his child, whether he likes it or not. Because that's the law.

I was seeing my old teaching assistant until the end of summer when I discovered he was already married, now I found out I am pregnant, I've messaged him but he told me to stop contacting him and being desperate thinking that I am lying? Anyone got any advice abortion is not an option for me

I'm pro life

The main question is what outcome are you after?
Judging by the information you've given it doesn't look possible for you and he to live happily ever after with your child.
So what are you wanting your future to hold and then I'd be happy to advise how you may wish to proceed towards that goal?

At least I will make him pay child maintenance

Okay that's your goal for him.
What about you?
What about your foetus?

I decided that I will definitely keep the baby he will soon get a shock as he doesn't believe it still

Yes but what are your plans for you?

What is your age first and foremost?

I'm pro life

That is an emotional reason.
It is not a clear logical reason.
With major decisions in your life, it's better to make them on the basis of pure cold hard logic.
Please sit down and think about this with as much clear thinking logic as you can.
You still might arrive at a decision where you should keep the baby. You might arrive at a decision where you proceed straight on to an abortion.
You don't want to get into a situation where you make a decision now that's based on emotion, and then 2 years down the line and for ever more regret your decision and think what might have been if you made a different decision.
Talking to the wisest adult you know might help. Someone that can give you good guidance on this.

I'm not having an abortion

Yes but what are your plans for you?
What is your age first and foremost?

I believe they’re 19.

I'm 19, I don't know what my life plans are if thats what you mean but surely I can request he pays child maintenance

I was seeing my old teaching assistant until the end of summer when I discovered he was already married, now I found out I am pregnant, I've messaged him but he told me to stop contacting him and being desperate thinking that I am lying? Anyone got any advice abortion is not an option for me

That's something you need to speak to a solicitor or citizens advice bureau about to find out what exactly are your rights regarding the (unproven) father paying maintenance. The Student Room community are not qualified in family law to support you through this.
From reading the threads you have made, my concern is more that there are three roles here - him, you, baby. You're mainly concentrating on him. Instead, focus on your health and start to think about what you need to do now to get organised and stay healthy throughout your pregnancy.
The only other suggestion I would make regarding the man would be to try to establish where he works now if you don't know already. If he still works in a school I'm certain a headteacher would wish to know about this. It being legal means I don't think there is anything actionable from an employment perspective. But from a safeguarding children point of view this is something I would wish to be aware of, due to the age gap between you and your status as a former pupil under his care.

He still works at a school

I didn't ask, I gave you advice in case you did - it's up to you whether to follow it.
Is there anything else you would like advice about?

Alright you don't have to patronise me