So what do you want now OP? Apart from him to change his mind because that might not happen.
If you need to work more to earn more to be able to pay housing for you separately then he needs to do more childcare and work less.
I would get angry if my H had done this with kids your age. He can't just waltz off to a bachelor pad and live the life of Riley. I would make his life as opposite of happy go lucky as you can
Every other weekend drop kids at his single pad and tell them you will have them back after work on Monday. That sort of thing.
Men will say they want 50/50 to not pay maintenance but they drop kids to mum before school and pick them up after work keeping the mum skint and having to do all the nursery/school runs and just having them in the evenings and don't do "boring" stuff like homework and reading.
So fine if he is going to walk out of the marriage that's one thing but he can't walk out on his kids.
So make him do the kid work. Go grocery shopping for their food, clubs, park, swimming on his own. Wash their clothes.
He will soon realise that he isn't Mr Ripley.
Get stubborn OP don't be a doormat. Remember this was his decision his alone do not feel sorry for him.