Antlers, I'm sorry you're now facing this. I don't know what your legal options are, but could it be time to get some counseling for your kids? Perhaps a third party could work with them to counter this ugly influence they're getting from their mother and sister. A safe haven, where they can talk about it without feeling like they're in the middle.
Shocking for me to say, but that's the exact kind of work my W does in her practice, so I have some knowledge of it. There are therapists that specialize in this sort of thing. I'm sure your young kids hate hearing that stuff about you, and it's harming them.
