I found out my father has cancer.. what can I do to make it feel better?

Listen I just found this out but my father has cancer in his mouth (tongue). He has been through many operations and it always comes back, years ago docters thought it was just an infection and that it might later turn into cancer but all the surgeries and operations have left his tongue looking weird, he cannot taste food but he doesn't let that stop him worse of all it keeps on coming back. This is going to be his last one for he has been diagnosed with stage 2 cancer, he has a few options one of them being removing his entire bottom jaw bone plus radiation but he doesnt want to do it because it will mutate part of his face. He has a daughter ( my younger sister) but she doesnt know. I have had such great memories with this man, he has taught me so much. I keep on having flash backs of my past with him reading books and watching movies together and playing games. I pretend like it doesn't really bother me (trying to keep positive) but when no one is around and im in the shower i cry. I never cry, it felt weird crying for the first time in over 5 years. But the sad thing is I have a feeling he won't last long because like I said it keeps on coming back. This is my first family member I "might" lose so I'm new to all of this. I wish he could stay long enough to see me get married or graduate University but I'm only 15. I mean when someone dies theres no way of talking to them.. or seeing them, all I can do is look at a photo and have memories/ flash backs that will make me feel even worse. Now what I'm asking you all is what the hell can I do to make myself feel better, i forgot to mention he lives far away he and my mom split up some time ago, so i only get to see him in the summer or christmas. He drops by ever now and than to see all his family in my home town or for his work, but he doesnt even let the thought of cancer bug him he says life is it short. I feel like i have a big knive going through my chest.I know some of you are going to say I shouldn't feel like hes already dead and I try not too, but its harder than it seems, I'm not ready to lose him. Any advice to make this experience a less bumpy ride?