Once someone gets enmeshed in something like this, I think it's hard for some people to know when to walk away or scale down. They don't want to admit failure and don't want to think that all their hard work didn't result in what they wanted. Thinking that wealth is also just around the corner can be addictive as well, so you need to keep this in mind as to how far you want to support him.
when I'm sick and need him to care for me he doesn't seem to understand that this is what I'd expected from our life together, and that's probably because we never discussed it
Could you elaborate on this? When you're sick, does he not support you?? If so, that's a major problem and red flag. It also doesn't count very much if he does things begrudgingly.
Certain things don't have to be discussed by the way, because they're so bloody obvious. If you're in a long term relationship and have a child together, it should be absolutely obvious and an automatic given that you expect to be supported when you're not feeling 100%, and you shouldn't have to be at death's door before getting that either.
I helped you achieve your ambition of having a family, so now I want you to help me achieve my ambition of being a successful entrepreneur
There is so much behind this claim.
Did he feel coerced into having a family? Does he have reason to be resentful?
If it was a shared ambition, then it looks like he has just made-up a deal you never knew you signed up for. It's a bit worrying really, because it suggests he didn't really want to have children, or he wasn't that bothered, and is now using this to it's absolute maximum.
OP - do you think there was a possibility that he saw you as capital into his business? That he didn't mind having a child with you because the pay-off of your salary, your financial support and anything else you give was worth it for him? I know it's extreme but people do use other people for money.