Been there twice. First DH had bowel cancer, died aged 44, chemo was palliative only and didn't work anyway, but that was over 20 years ago. I had 2 mid-teen daughters at the time, and it was a very lonely situation. Second DH developed early onset dementia 3 years after we got together, and then, in 2008, an emergency resection for bowel cancer, followed by 8 cycles of chemo. It was practically difficult dealing with chemo whilst DH had moderate dementia. It was, however, successful, and he made the 5 year survival, only to die last year of his dementia. Please don't think I'm unsympathetic, but there really is nothing lonelier than being the partner of someone with dementia! Cancer might kill a person, but it doesn't steal their core being like a thief in the night! With just about 2 decades of experience of this, I'd have to say, value the good things of the life you've got and don't dwell too much on the future. Every good wish for your journey.