OP, this man has seen you coming, I'm afraid.
Let's look at what happened.
He was living alone (or with his kids), paying all his bills and doing all of his own housework.
He met you and persuaded you to live with him, with the vague promise that in the future he would commit to you. Frankly, you shouldn't have settled for this, not when you had children young enough to live with you. Just out of interest, were you renting prior to meeting him or were you on a mortgage?
So you moved in. You took over the housework, I'm betting. Yes, I'm sure he does do some, but be honest - how much do you do, percentage-wise?
You also paid a lot towards his bills. Only it wasn't just half of the water bill, half of the gas bill etc, was it? You were paying him rent and he, as the landlord, was paying that rent off on his mortgage, which of course he has the right to do.
So the consequence of his living with you was that he got housework done and someone to pay a proportion of his mortgage.
He also persuaded you that if you played your cards right, that if you became a worth person, he might, just might, marry you. You then felt yourself change, so that you were needy and worried.
He's not daft, is he?
He's not a prize, you know. He's not up for grabs. He knows he won't marry you - nothing wrong with you - he's living with you, after all, but he's got it really nice at the moment - someone to do his housework, someone to pay his mortgage... why on earth should he marry you?
Wake up and look at what you've got into. He could've said, "Look, I'm paying the bills anyway; put your money in a separate account and it can pay for the wedding." He didn't.
I think you are vastly underselling yourself. Why shouldn't he buy you presents? Why shouldn't you be worth marrying? Who the hell does he think he is?