Welcome to the site Decimaldancer. I hope that terry gets to read your post, but we don't know for sure whether he reads the site.
I'm so sorry for your loss - although there's a great deal of dignity with the way your father chose to go and although I'm sure you'll all miss him, I also suspect you are thankful that he's no longer suffering. He went the way he wanted to go - and that has to be a good thing.
Best wishes to you and yours,
Wyrd bið ful āræd.
"Coffee. The finest organic suspension ever devised. I beat the Borg with it."
- Capt. Kathryn Janeway