Dad battled Parkinsons for almost 10 years and for the last few, was a shell of his former self. After he passed I was able to get out of the problems of his decline and focus on his very remarkable life. While he was alive I just focused on his condition. I wish I had spent more time reminiscing with him about great times when I was a kid.
Since his death 2 1/2 years ago I think of him with joy in my heart and remember the REAL Bob Wallace, not the way he lived out the last few years.
Not sure if your Dad's death was sudden or not, but I pray that you are able to focus on his very best qualities and accept the challenge to live up to them (as I'm sure you do every day!)
My condolences on your loss.