My thoughts are with you. My father, too, had a long decline before he died, from heart disease, diabetes, and renal failure. It is hard on the family. I was 900 miles away for those last years, and while I didn't have the burden of primary care, I did use that time to make him as emotionally comfortable as I could. Towards the end, the phone was inadequate. No one knew he was about to go, but I guess I must have had ESP or something, because I left NY for Illinois early on a Saturday morning on an impulse, and was on the road when he died.
It's a hard thing.