Welcome to the forum. I am so sorry to hear about you Dad. Sounds like you're getting good advice from the book. I think you're spot on doing something for yourself. If you're calmer that will help your BPD, so double whammy. I also had to keep out of the house as much as possible when I was living with my BPD.
We suggested our BPD went to Yoga, because she can't sit still and is permanently anxious. After telling me how deeply insulted she was, my dad swept in behind and offered to drive her there. She was asked to leave because she couldn't keep quiet. "How can anyone sit still of more than five minutes, it's not natural !" she told me.
Anyway do tell us more, you'll probably find the bizarre behaviour of your mom, sounds very familiar to people here. A BPD isn’t really interested in stuff that doesn’t help them, so if you do something for yourself, make sure she knows why that is to her benefit. As for her "stupid ass" comment, she’s just fishing for sympathy or there may have been a donkey in the room.