I went through the same exact thing in December when my dad was going through open surgery. To be whole heartedly honest with u, I am married and living in Chicago. I am 28 yrs old, have been married for 2.5 yrs, and lets just say I have been through hell and back, not a happy marriage at the least, but we are working on it. Anyway, however bad it was could not compare to hearing my mom tell me, "your dad has something and he is going to take care of it." I knew it was cancer.
I went to NY to be there for him during the surgery process. Yes, seeing him having to prep for the surgery was SO HARD. I had to fight back my tears the whole time and pretend that it was all a piece of cake. He too was acting like it was no big deal. Fast forward, he had the surgery and has recovered since then.
Once you begin to accept it, you will be better able to deal with it. Yes, it's still on my mind every freakin minute of the day, but now I just say to myself, we are doing everything we can to fight this and everytime my dad turns around I will be right behind him every step of the way. For some reason, just being present makes me feel a WHOLE lot better.
(If you are thinking what does my marriage have to do with anything, it's just to help you put things in perspective. When you think life is bad, it can always get worse. You just have to learn to be grateful for everyday.)