How can I help my dad?

My dad was diagnosed with cancer for the second time. Unlike the first time, when he got surgery and chemotherapy to remove thaw cancer and the tumor, he is refusing treatment. I have come to understand an accept his decision. Now I just want to make life easier for him just a little. I am underage so there is not much I can do. But apart from telling him that I love him what can I do? I tell him that I love him and he pushes me away. He blames me if I'm in the room and something goes wrong.  I understand that he is in pain and I still love him and want him to be happy but how can I do that? My dad has stage 4 stomach cancer and he is convinced that he was misdiagnosed although he weights less than 100 pounds. I don't know if it's because of his denial that he is refusing to get a total gastrectomy to remove his tumor or if it's really his choice. The doctors gave approximately a year to live and throughout that year he has been at home watching tv. Is that depressision? The year is almost coming to an end and he hasn't changed his mind about treatment or wants to talk about the pain that he is going through. How can I help him? What should I tell him? What should I ask him? what should I do when he is crying in pain? I try to hold his hand but he is trying to withdraw for me. My mom works and my little sister and I have to go to school. He is left all alone. What can I do for him?