You can't make him stay with you.
But he can't just walk away from your child, well I guess he could but he still has to financially provide.
So what are you going to do OP?
I would advise you change your loyalties from your husband to your child.
So you could ask H how he thinks the split will work, many men try the 50/50 to not pay you maintenances but that 50/50 means dropping to you in morning so you still have to do nursery/school run and collecting after their working day, meaning you still have to do school/nursery pick up. So don't fall for that, 50/50 means 50% of all child costs, winter coats, school trips, uniform, the lot, get this legally drawn up and 50/50 means 50% all day, each week, all holidays.
Just be aware, he might play on your love for your child to enable him to be 50/50 Disney dad, continue to earn what he does, get promoted, whilst you end up financially stunted. Or he pays you decently to provide a decent, loving home for your child.
You need to put a business head on OP.
Don't play your cards out in the open.
He will play on your weaknesses if he can.
He might then "decide" he wants to stay and try and make the marriage work. If that happens at that point, if you want to, you put a list of what he needs to agree to for you to even consider that.
And again don't agree to anything straight away. Say you need to sleep on "x" whatever X is.