How can I cope?...?

Some of you already know about my family cirstances -- My sister is dying of congestive heart failure after suffering multiple strokes back in '04. The congestive heart failure came about just recently, she has pretty severe edema, had bloodwork done, and the diagnosis of heart failure was officially made. My parents have been her caregivers for 3 years in April. It's been exhausting for them, of course, but we have tried to help whenever possible. On top of crying off and on about my sister, I am now faced with stressing over my Dad's new health issue/s. He's having a colonoscopy done soon. I was at my parents' house earlier today, and on the table were instructions for the days before his test... along with a brochure about colon cancer. When I heard about his main symptom a couple of weeks ago (perhaps less), in the back of my mind was the C word, but I just didn't want to think about it. However, when I saw the brochure, naturally I'm silently screaming. :(