Hi M1A1----you've been in my thoughts and prayers. It takes a lot of inner strength to sit by, care for and watch a dying loved one. Drunk or sober, you'll always know you were there for your father in the end.
In my case and in retrospect (which is always easy to do), I would wave a magic wand and be sober when my mother was dying. It wouldn't have helped the pain but I would have done a better job taking care of her affairs.
Thinking of you.... ((Hugs))