I'm sorry to hear about your dad's terrible illness and decline. I lost my own dad last August. He was 87, and I'm 65, so perhaps I was able to get through it a bit easier, knowing that it was about the right time for him to go anyway (if there is such a thing).
I won't try to counsel you, but I will say that I think you're doing the healthy thing by simply unburdening yourself by sharing your grief with us. I know from having recently gone through this loss, that it helps tremendously.
One thing that helped me more than anything else, was to just let the grief roll out of me. Like any typical guy, it took me a couple days to let myself go, but when I did, a torrent of grief came out of me. I haven't cried that hard in too long to remember, and it went on for hours. But when it was over, I was in much, much better shape, than in the few days since his passing.
After that I was able to function, and managed all the logistics to get myself to his service, some 1,500 miles away. I was also in good shape to handle the heavy grief of other family members during that visit, because I'd already exhausted my own.
Peace to you, my friend.
>> I lost my own dad last August.
Condolences, FRiend.