I feel like this is some type of fairytale where you have cast yourself as Cinderella and her the evil sm and you will not if indeed you are nearly 40, take any accountability for your actions here.
She's evil and nasty but you let her be childcare.
Your nervous about telling her because your worried about her reaction but I don't think so worried you won't use her as childcare.
Adult fathers don't supplement their adult children lifestyles to cope because people work full time for a living and that's not a role of a dad.
Think of it this way your being bought to be a decent human being to your sm. every time he gives you money it's to essentially shut you up.
Your playing the pick me dance and at your age and the fact she's still around should tell you something. You haven't been able to get in between their marriage. That's gotta sting.
You are talking like a child and I suspect either than your younger than you are or have some developmental issues which makes these concepts harder to grasp so I'm gonna be very very direct.
Your pregnancy has nothing to do with her. The things you have stated don't make her evil at all, most people who really hate their sm won't leave their kids with her.
It's fine to go I just wanna spend time with dad and cut sm out. But that means you don't have childcare. Make your choice and stop painting yourself as a victim. Because your not.
I have seen questionable actions by sm and sd on this board and what you have stated isn't any of those things. I say this as a mum with a Dd who has a Dd. If you were my daughter I would tell you to politely grow up.