Im sorry.
one piece of advice I ignored was that it really helps to talk about your grief with other people.
Part of that grief will be your rage towards members of your family for what you see as letting him die right now. We cannot tell you its all right because its not, but like Dan said above, you will eventually feel better with time, coming to terms with the loss is a lot easier if you share what your going through with others in a similar position. It will take years. Make sure you talk to your family, don't let words said in anger and grief break you guys apart.
I didn't speak to one of my uncles for years after my mother died, because in my eyes he couldn't be bothered to call his deceased sisters children for over a year after she died. Now i realize he didn't know what to say, and was dealing with his own grief.
I was a kid when this happened to me, I considered talking about my grief "weakness".
lol, if only I had some extra wisdom back then. Now I realize that hiding it from people was actually weakness, and it made my process of grieving years long. It became a hidden wound that an inadvertent comment would tear open, and I would feel just as bad as if things had just happened. This will happen to you, you will eventually build armor against it, but it will be painful.
People are compassionate, more people than you realize have undergone these situations. One thing thats painful is that you never realize just how much time average people spend talking about their parents in daily conversation until you're in a position where you are tying to hide loss of one or both.
Also you will not believe what people who haven't undergone a loss like this consider an appropriate comment. Be prepared for some ridiculous behavior from individuals, people care, but you might have to cut them some slack, as the most amazing stuff pops out of peoples mouths when they don't know what to say, but feel they must say something.
Starting this thread was a good idea, another good idea is joining a support group, visiting forums where people discuss their grief, doing what you can to understand that you are not alone in these feelings.