Re: 3 years later and showing signs of starting again.
Your STBX is unstable, she's not a good mom and there isn't a damn thing that you can do about that.
I wouldn't poison your kids against her, but rest assured, they will figure it out eventually and it will leave scars.
Your goal should be to protect your kids and protect yourself as best you can and if that means minimizing all contact with her then do it. It also means you get the best deal for you and for your kids in the D; money wise and visitation wise.
You fight for them and do whatever you have to do to achieve that goal.