Lost my dad in November in very similar circumstances to yours Roscoe, its hard.
As said previously, be there for him, talk to him, hold his hand...I know dad appreciated everyone being there.
Apologies if i say anything out of turn or touch a nerve, but there is a sense of inevitability as well, which for us helped a bit. We knew, even our mum, his wife knew deep down, dad knew deep down he couldnt go on like that. It was very peaceful as well, that helped too.
There are no words really, everyone reacts in their own way. We all miss dad dearly, but in a strange way, we all seem to have accepted his passing, that inevitability seems to have soothed our mourning for him.