It is a tough time surikell , i was 23 when my mother died of cancer , my dad was in a mess too, and if the truth be known he never really got over it.
He died 3 years ago (14 years after my mother) but i think if he had ever met a decent woman , rather than the horrible bitch that he actually did meet, things would have actually been a lot easier for himself and his kids, in the years after.
The thing is , it does get easier, although you dont forget ever.
Your dad will recover im sure , and after a while you just crack on with the rest of your lives.
Good luck.