Im sorry to hear that you are going through this. I hope he isn't suffering. And when he passes realize that he won't be suffering anymore. When it comes to these situations I try to remember that we are all going to die and try to look at it as a transition, though in the heat of grief that is tough. Also think of this too, your dad will never totally leave you, because he is a part of you. Whenever I look in the mirror I see a little bit of my dad, some of my mannerisms and expressions. Either way as cliche as it sounds, I am sorry for your lose.
"Today a young man on acid realized that all matter is merely energy condensed to a slow vibration, that we are all one consciousness experiencing itself subjectively, there is no such thing as death, life is only a dream, and we are the imagination of ourselves. Here’s Tom with the weather."