This is a sad situation, and I feel for you - and your dad! I had gone through such myself, and it is never easy.
Time will heal those wounds, eventually. I just hope a sensible solution will present itself.
I take from your post that what tears you apart is the sacrifice you made for them, and now it is all for nothing, since in all that bitterness toward one another the financial aspects will suffer. If they would realize what suffering this is causing you, then maybe they come to their senses. While you are not an infant anymore, but somehow I think the judgement of Solomon might be a parable your parents should consider.