Well, it’s not normal. It’s terrifying. Whatever happened in her past does not give your mother license to hurt her children. No kid should be constantly worried about what she’ll find when she opens a door in her home.
Your mother sounds seriously mentally ill. Your dad sounds either overwhelmed or in denial. He and your sister are just keeping their heads down so they won’t be targeted. Instead, he should be your ally and he should be getting his wife some serious help.
I’m sorry your mom’s doctors have written off your reports as teen drama. Do try again. But this time, get an adult to help you. If your dad won’t cooperate, please talk to a trusted relative, teacher or your school nurse or guidance counselor. They may be able to help your dad know who to contact and how to get good help. If that doesn’t work, consider staying with a relative for awhile to get yourself out of the way of your mom’s anger.
I know this is really, really hard to do. But I hope you can keep the perspective that you are not responsible if your mother succeeds in committing suicide. Her problems are bigger than you can handle on your own. As much as you love her, you can’t give her the professional help she needs. Your dad and her doctors need to do what they can to take charge to avoid a tragedy.
I wish you well.