If you want to feel better about this whole situation, try making your dad feel better during his last days of life. The knowledge that you brought joy to his final days will give you a snese of peace about his dying.

Call your dad, every day, tell him that you love him, tell him that he was the greatest dad in the world. Remind him of things the two of you did together when you were younger, the fishing trip, Disneyland, whatever. Recount your experiences step by step. But call him every day; it will mean a lot to him.

Look, life is a terminal condition. No one gets out alive. Your dad knows he is dying. The nicest thing you could do for him right now is to make him feel that he was a success at the most important job of his life - being a father.

By all means, visit him as soon you can. You'll be kicking yourself in the ass for a long time if you don't