@TheDaringOchreQuail
Your feelings are your own, and you're entitled to them. But try to understand that this hatred you have for your mum is not healthy and is holding you back from being completely happy.
The dynamics of your parent's relationship were in place long before you were born. Your dad started conditioning your mum to accept his abuse even before they were married. So think about that. If you're an adult and out of the house, that means it's been going on for decades. Decades. Decades in which she was subjected to 'punishment' if she didn't 'go with the programme'. And sometimes the fear of emotional abuse can be worse than the fear of physical abuse.
If you read up on the 'boiled frog' analogy you'll understand that this happened so slowly and insidiously that she didn't even know it was happening. 'Walking on eggshells' and all that goes with it is normal' to her. Even as she begs you to 'cover for her' it's normal to her. And when she says "It's just the way Dad is" she isn't excusing his 'bad behaviour', she truly believes it's no difference than saying "Dad doesn't like carrots". And in her head, you 'catering' to his abuse is no different than her feeling that you shouldn't give your dad carrots.
I know you're thinking "But she could leave" to all of this. And I understand. But it's not as simple as just walking away. She has been psychologically damaged by him and it's been going on for decades. She's as held fast by her mental 'chains' as if they were solid iron. And the more you try to argue with her 'to free her', the closer she'll hold those chains to herself. Because it's all she knows. It's all she has.
If you really want to help your mum (and I hope you do), then you'll get counseling to really understand how emotional abuse 'works' and to try to put your feeling about this, and about her, into a healthier place in your own mind. Once you do this, you may actually be in a position to help her, if that time ever comes. I'm not saying it ever will, but wouldn't it be nice to be ready, if it does?