Hi,
Unfortunately, I know all too well what you're going through now. My dad was diagnosed with hepatocellular carcinoma last October, and passed away on March 22 , only 5 months later. At his diagnosis, the doctors told us he'd have about 6 months without any treatment, or 9 months with treatment. Of course we were willing to try anything, but there weren't many options available to him. Because he had numerous tumors on the liver, he was not a candidate for cyberknife surgery, RFA, or anything else except Nexavar. He tolerated it fairly well, and remained on it until the week before his death. I remember having all the same thoughts you mentioned about this being the last birthday, Thanksgiving, Christmas, etc. that I'd have to spend with him. It was made even worse by the fact that my mom was killed in a car accident 6 months earlier, in March 2007, so in addition to knowing it was a season of "lasts" with my dad, it was also a season of "firsts" regarding my mom....first Thanksgiving, Christmas, etc. without her. Add to that the fact that my little brother passed away in 2004, and I've lost almost my entire family in 3 & 1/2 years. I have one sister, and we've become incredibly close throughout this ordeal, despite the fact that we live 1500 miles apart.
I think what has helped me deal with the depression and other feelings I still continue to have is knowing I did everything I could to try and help him. I sold my home, quit my job, and moved 300 miles to live with my father and help him out after my mom died. He had several other health problems before cancer, and was unable to live alone. I had almost exactly 1 year to the day with him, and I wouldn't trade that time for anything in the world. We got to know each other as adults better than we ever had before, and I'm so thankful for the time that we had. I guess if I can give any advice to you, it would be to spend as much time as possible with him and enjoy it while it lasts. I can remember just staring at him when he wasn't looking, trying to burn the images into my memory so that I'd have them to hold onto after he was gone. Prayer has helped me tremendously, as well.
If I can answer any questions you might have, I'd be happy to help. I'll keep you and your family in my prayers.