oof. Sounds like a lot of potholes are coming your way.
Honestly? Call her and set the ground rules.
Do you want to go back to that drama and chaos? I certainly wouldn't. If it were me, I'd say, "I'm coming to spend time with the kids, so don't get any ideas about us fooling around or getting back together."
Ugh. That is so low of her...and if you are her warm place for the holidays she's going to pull out all the stops.