I went through this a few months ago and it was heartbreaking. The only condolence was knowing she would no longer suffer. But it was devastating, nonetheless. I'm sorry you have to go through it, but just remember all the love and happiness you were able to provide for her. Just hold her and love her through the end. That is the best advice that I can give.
"What can you expect from a bunch of seitan worshippers?" - Reginald Tresilian