It's not about losing hope, it's just about accepting what comes. What will be will be. Maybe I'm overly logical about these things but I figure its either:

1. You believe in God and an afterlife. If she was a good person and it sounds like she was, then she will be in a lot better place than you when the time comes.
2. You believe that the lights just go out when we die, in which case all a person's pains and burdens end as well.

In either case, it would be better (if it's gotten to that point) to let them know that it's OK to let go, and that you accept that. Though we all naturally want to hold on to the people we love, we shouldn't put a burden on them to suffer more than they need to in order to help us avoid the pain of loss.

Maybe I'm just pissing off people even more now, but it's just that dying is not unnatural. It's the one thing we are all guaranteed to do at some point. You will die some day. Do you want your loved ones to suffer greatly when that day comes, or would you prefer that they celebrate your life as it was, accept your death as the natural course of events, and carry forward, not forgetting you but not letting your passing deprive them of enjoyment of the time that they themselves have left? I think I'd really prefer the latter.

Anyway, that's all I'm going to say about that, in order to avoid digging myself even deeper into a hole. But I do say these things in order to try to help, as best I know how.