Hi todayistheday!
This right here is the right attitude to have:
I sort of right now have the attitude, let's just do whatever we want... .we'll get raged upon no matter what we do, so might as well do what we want.
You've got this. As strange as it may seem, once you understand that she will do/say/be exactly what she does/says/is, the freer you will feel. Stop twisting yourself inside out trying to avoid rages and upsets since it does not work, and stop trying to find just the right words to express just the right things to please her because it will never happen.
I've always figured if I can't win (aka will be screwed no matter what I do), I might as well do or say what I feel good doing and saying. Avoidance never worked for me. Twisting myself inside out never worked and it caused me nothing but pain and frustration, so I stopped doing those things. I've always hated no win situations so I learned to either change the rules or not play the game.
Freedom comes from within and you can have that regardless of what she does through acceptance. Would it be better and easier if she would change and if you could find just the right words and do just the right things so she would act like a normal person? Sure it would. But she is not normal. Accept that.
As for your father, as sad as it is, he made his choice a long time ago. It is not possible for you to protect him. All you can do is love and support him, but leave him to deal with the consequences of his own life choices.