Well you are financially joined, so not it's not your business. It's up to him if he wants to share.
OP, what are you thinking?
Why dont you work fulltime? Not judging just asking why?
Look, I work full time. I have 2 kids full time. I manage to keep the house clean and tidy, look after the kids, do the shopping, cook and look after us. I have a dp who doesnt live here and has picked up ds on occasion if I have needed him to.
There is absolutely no reason he needs an unpaid skivvy doing all these things for him, because the poor love has kids and works full time.
If you lived together and did all this I would still say you are a mug. Should work fulltime to ensure full financial security and stop doing it all. It would be slightly different if you lived together, because the house would be shared so jobs done in the house were for both of you.
But you are running his house and your own.
This is a ridiculous set up