Just since everyone else is saying to run, and I really don’t think that’s necessary, I just want to reitterate this. If you can get him to approve your establishing your house rules for when she is with you, then you’re good to go. And for that, just keep nagging, nagging, nagging. And good sex. Good sex and nagging.
Evil, manipulative, true. But do it well and he won’t mind a bit.