I'm really sorry to hear about your situation. I am going through a similar situation with my dad. It really sucks watching someone go through that kind of pain, but I think it is even harder when your feelings for them aren't all good. I have no idea what the answer is but I think at this point you have to worry about yourself. When my dad dies I want to be ok with the way I treated him in the final months. I'm not sure it is worth trying to fix things at this point because he is so wrapped up in himself, as usual. Hang in there.