Let her be someone else's problem now. It's obvious her family didn't think her behavior was an issue and expected you to just put up with it. Families like that, it's like they already know their person's inappropriate behavior will never change so they've stopped scolding a long time ago. You either accept or move on. Otherwise, you're a bad person for complaining as long as you choose to stay.
Just be thankful that you don't have to pretend to give a sh.it about them anymore.
People like that certainly makes it much easier to move on.