Wolf, I guess my only feedback is to try to keep your interactions with her in front of the kids and about the kids above board. It is easy to fall into the trap of reacting in kind, but that is not in your kids best interests. You cannot control your X, and she sounds like a real piece of work, but your kids will look back with discernment about how their parents acted. If they see her bad behavior and that you reacted with as much grace and dignity as possible, that is what they will take with them.
My original response to your post was to make you aware that while your X's behavior isn't helping things, you need to be sensitive to your kids' perception of what is going on in their lives. They see you with a live in girlfriend (a new "mom" in their lives). Further they are facing the unknown of having their dad be a father to a new child with this live-in GF, and what that will mean to them in regard to their relationship with you. Lots of kids have seen their parents move on with new people, father new children, and treat the kids from their first marriage, um, differently. So please be sensitive to that since your kids are in very difficult age categories for dealing with these kinds of things.
Sorry you have to deal with a psycho XW, no one signs up for that. But remember you will be judged based on your actions, not hers.
M(53), W(54),D(19) M-23, T-25 Bomb Drop - Dec.23, 2017 Ring and Piecing since March 2018