What protections are in please should you break up? He holds all the cards, the mortgage is in his name & you won't have the resources to fight him in court over the share of the mortgage you have paid.
Look at it from that view: you are back on your feet after divorce, renting, receive benefits which help you work part time, know that you will increase your work hours as the kids grow up, and you have bad credit
That's all fine. But such a drastic change - all in his favour - will be a LOT to cope with. Not only will you have to work more hours to cover childcare and uproot your kids, he will expect you to do a less than 50/50 share of housework and maintenance, I'm sure, because you don't earn as much.
You will run yourself ragged just trying to keep things together. Kids will be neglected as you have less time, he will probably grumble if you're not around to pick up after this big blended household. He holds the keys.
You're paying him rent to live and work for him as well? For a man who earns 5 times your wage but still wants to split things equally?
I'm saying this as I would to a friend: please stay put. Your relationship can still progress, but you are giving away your power. It's a fresh relationship and he could dump you on a whim, you will feel it harder to leave because you will have sunk so much into this.
You will be starting from scratch again, like you're at the bottom of a slide. And worse off than having credit card debt, you will have helped pay off the mortgage of his house
Please don't be blinkered by empty promises or sex. This is such a bad deal for you, I'm genuinely sad