I think you leave the discussion of his cheating for another day. It has no relevance to his relationship with his children.
It would be nice if each of you could foster a good relationship between the other and the children, and show respect in everything you say to the kids about the other. So I think you can say that Friday night is an early-to-bed night because they've had school or day care all week, and Daddy has had work. The kids are probably all wound up, so they need to go to bed at a decent hour. But we can assume that they get up early on Saturday so they have all day with Daddy, and isn't that fun, kids? Isn't it the same amount of "quality time" whether it's at 9 PM or 9 AM?? So if you can put your resentment of his attitude aside and find some balance, that would be better for everyone.
Saturday night can be the late night but they are sleeping late on Sunday and therefore losing morning time with you. So I'd try to help your daughter find the positive, whether it's having breakfast and lunch with Daddy or watching morning cartoons or enjoying more daylight. Anything. And you can support the idea of "Daddy's house, Daddy's rules; Mommy's house, Mommy's rules." If you can have a civil discussion with him to share what your daughter said and how you think you can answer it so that it's supportive of him, great. If you can ask him what he says and what he'd like you to say, even better. Mention that you have a strict bedtime Sunday through Thursday, so you get that they are tired on Fridays and may get cranky, so you support his decision. I think it would be great if he could foster a good relationship too - yes it's his job, but if you have them most of the time, it's only natural that they are going to look to you as the boss and that you will have to do more to ease them into time with Dad since it's the anomaly.
Kids cry when they go back and forth between Mom and Dad. Kids cry when they are with both parents and one has a rule they don't like. Many kids don't transition well from one house to the other any better than they transition from TV to the dinner table or from bath time to bedtime. You have to get to the point where it doesn't break your heart. You see him as the cause of her distress, but when she doesn't like something you do or she has a tantrum/meltdown, do you blame yourself? Or do you say, "Kids are like that sometimes"??
Just because he was a lousy partner to you doesn't mean he isn't and can't be a good father. In fact, spending time with daughters may make him have a little more respect for females - I'm sure he wouldn't want anyone to hurt them the way he hurt you, so maybe there's room for personal growth on his part by having empathy for his own daughters.
I think the more you can look at him as someone with whom you made 2 beautiful children, the calmer your own life will be, the easier it will for him to not feel your resentment (even if his past behavior earned that), and the calmer your kids will be.