Obviously I know nothing about your family or the current stability of the relationships, but does your dad have any ideas or advice, having been through this himself? Could he maybe relate to her on a level that you and your mom can't, or tell her the details of his experience and why she should seek treatment immediately?
I'm very sorry you're going through this and feeling so helpless. It's always difficult to watch loved ones struggle.
He's tried but she shuts him out. She's still angry with him for his abusive past. In her rational mind, she knows it was his bi-polar and he did things that in his sane state he would never do. In fact he does not even remember most of the abuse because he has the type of bi-polar that causes black outs. My sister has the same as she often forgets days at a time.
But when she's manic, she just gets so angry with everyone. Including my mother. She blames my mom for the abuse my dad inflicted on her asking why my mom stayed. My mom feels terrible about it but she was so mentally beat down by my dads abuse that she couldn't think clearly. My mom has apologized and both my mom and dad have agreed to go to family counseling. Then she just screams at them saying she doesn't need medication and she doesn't need counseling she just NEEDS her family to support her. BUT then she then turns around and says that we need to leave her alone.
And no she isn't on any medication. She says she doesn't need it. But yet she constantly self medicates with alcohol. Half of the time I can't tell if she's drunk or just in a manic state.