Caco,
my Dad died of congestive heart failure this March. He passed in a nursing home, but under hospice care. I think that, when things start going squirrelly, the issue of quality of life is important, but so are your Dad's wishes. He is undoubtedly thinking of you, and his wife, and maybe not so much of what he wants for himself. It is possible that an 'outsider' - a social worker, or a pastor knowledgeable in this area, might be able to sort things out with him better than those so near and dear to him. The hospice nurses, aids and social workers helped immeasurably in the last weeks - both with the physical and the spiritual aspects of dying. It was remarkable to see.
Please remember, as you are on this path, that no matter how hard you try, you cannot give your father youth and health: that is not humanly possible, and you can only do what is humanly possible.
What you can give is love, and the joy of companionship, and the knowledge that you are his beloved daughter. Not all parents are so lucky.
We will always second-guess ourselves and our decisions. My Dad should have gone into hospice sooner - but he was helping care for our old dog - with, really, the last of his strength. He would have been more comfortable physically in hospice, but I think caring for the dog was more important for him. When she passed, it was time for him to follow.
Take care of yourself, Caco, this is a difficult time for everyone.
Maria