Why does Eddie feel the "emptiest anger" when his father passes away?

Eddie had no atonement with his father. Eddie hated his father and was unable to reconcile all that hatred. Eddie realizes his father, like himself, was a very flawed individual. There was no joy to be had in his death. There was a part of Eddie that wanted some sort of closure, some last minute connection with the man that had been his father. Even telling his father how much he hated him would have been something: instead Eddie only feels emptiness.