(((((((lostmymarbles)))))))))) She can't sue you for not bringing the children to visit. Your family sounds very toxic-especially your Mom, by the way you describe her.
Can you have contact with her as little as possible?
I'm in the process of letting go of my family because it's not a healthy relationship for me. Not as abusive as yours but it makes me feel really bad about myself.
I hope that you're okay.