How have you dealt with the death of a parent?

I'm 30 years old, my father just turned 53, mu first child, the first grandchild is due July. My dad is in such bad shape from cancer treatment and surgeries I don't know if he'll make it to July. He's in the hospital about every three weeks for a few days to a week at a time, so far I have been very positive and hopefully that each time the Drs are just working out a kink, but this time I done know. His quality of life is so poor, he's depressed, the stress and sadness and guilt and anxiety I feel about him is overwhelming. Sometimes I think I can handle his death, but then I stop to think about it, and I picture him gone and I just break down. Does anyone whose lost a parent have any advice?