Sorry to hear this Eli. Try and hang in there and cherish your time with your dad. Family is the most important thing when this **** goes down.
Cancer is tough, both my parents lost their mothers to it just this year (my mom lost her dad to it 20 years ago). Their death's were last year/this year and only 5 months apart. My dad attended 7 funerals this year alone. He's 60 and most of his friends are dying off so I can't imagine how he must feel.
My Grandmother was a nurse and looking back, we think she knew something was going on but kept it to herself. She went pretty fast. She beat breast cancer, skin cancer and went through liver transplants years ago, but this one came out of no where. She didn't last a month. It was sad seeing her health decline each week I'd visit, especially after all the crap she went through previously.