Yeah, this really blows. You wanted so much for her to have a life after losing Chris, only for this to happen. Just heartbreaking. And I hear she sang at an event in New York in mid-January.
I had a friend die at 48 within a few months of being diagnosed with pancreatic cancer and was acquainted with a physician who died at 50 within 3 or 4 months of being diagnosed with the same type of lung cancer as Reeve; he'd never smoked, either.
All I can say is carpe diem. You just don't know when your card will get punched.