Been following your saga and wanted to send my warm wishes and also my deepest condolences concerning your father.
I come from a short lived family, my father at 74 is now the oldest on his side of the family after all the others passed away before reaching 65. Cherish him and enjoy whatever time allows.
I've seen loved ones go through sickness and deep mental degradation and it was the beautiful times that we'd had previously as a family that stick brightly in my mind, not the final condition of the mortal flesh. Just remember that we're all on the same race, some of us just reach the finish line faster than others.