J.E.
This probably goes without saying, but it sounds like she needs to be evaluated by a professional.
I say you are in charge of your own happiness. If you want to cut her off, cut her off. Next time she calls, tell her you will have no more contact with her which includes your children. If she shows up at your house or calls again, you will consider it harassment and file charges. You could make a stipulation to it if she agrees to seek counseling and the 2 of you get together with a mediator to decide how to move forward.
It sounds like she needs to do some growing up. My manic depressive biological father likes to blame everyone else for his flaws but himself. I finally decided that I would have no more contact with him and he didn't do even half of what your mother has done to you, but of course; my story is different. Many might say, why punish someone for being mentally ill? But sometimes you really have to distance yourself and let those people go for the sake of your own mental health.