Thank you mvgfwd, I can only hope I will remain strong.
So we have set the money he is going to contribute. H will watch the kids at our house during the weekdays while I work and one or two nights when I have class or go out. H has to have a key since he will be watching the kids during the day, picking up D3 from school etc...so I'm ok with that for now.
But this morning H told me D3 has to miss school today because he can't go pick her up. I asked why. He said he is helping someone move. (might be OW or OW's roomie? I don't know) I asked him to just go pick D3 up and go back to whatever he is doing, and he said no. D3 goes to preschool only part time, so not everyday and she is very looking forward to it. It just breaks my heart how H does not care. H used to adore D3 so much and I'm sure he still loves her, but his selfishness is winning lately.
SIL is very angry and she wants to talk to H. I don't think talking would do anything, but it's her brother. I'll try to take one day at a time.