So he wants you to be a sahm? Having never agreed to this, in fact agreed to the opposite? Where's all this come from op?
If you left, you'd get maintenance from him, seeing as he doesn't want to parent on the days he's not working he's unlikely to want 50/50 which would mean there was no maintenance to pay.
So, work it out. If you went back to work and paid the whole nursery bill and whatever you have to put in the bills what would your finances look like? Then work it out that if you left him, put your salary into the benefits calculator and his salary and the imagined time he'd have the baby and work out what the CMS payment would be. What would your financial position be then?
If you are feeling generous, you could do the calculations for him. If we stay together, I go back to work and we split the nursery bill, you'd be in this position. But if I left you, and you had to pay all the bills on your own, plus CMS, you'd be in this financial situation. Oh, and those precious me time days off would be probably be gone too.
Let him see the reality of the situations!