Another point I think you've missed is that I very much doubt he can actually buy a house without your deposit and salary!
Your part of the deposit would provide up to half. And your salary would provide approx £50ks worth of mortgage.
Essentially your income would enable him to get a house which is 1/3 more expensive than what he could on his own.
THIS is your power and opportunity to empower yourself.
Unless you're in a particularly cheap part of the UK, he probably can't afford to buy without you at all.
And given everything you've posted, I wouldn't buy with him or marry him. I'd ask him to leave.
If you start again on your own. You can work full time and he has to contribute equal share of child care costs and upkeep for DC. You could save for a house of your own then.
Just watch his face closely when you tell him your salary provides x amount of mortgage which he needs for "his" house and that you've changed your mind and you no longer want to commit to buying with him.
And when he rushes out to buy you that ring, don't accept. Tell him to go. He isn't interested in your relationship, just in it for himself.
And marriage. Well it's not security or emotional security unless both parties are committed. My mum has been married 4 times! My dad (first marriage), wasn't really interested so she chased him around and gave him an ultimatum. He married her but it clearly didn't last.
He was only interested in splitting the bills with someone and didn't really want marriage or children. Hence a bitter divorce and because he had set everything up to protect himself financially, mum got royally screwed over.
Take back control of your life now. Don't waste time.