Very sad story, but I think it's a good thing you've decided to open your heart here. Even the words of virtual friends are better then dealing with all this alone. My only experience with this kind of situation is that of losing a sister to cancer and the little advice I have to offer is stay strong. Don't break down in front of her, it will only make you both miserable. She already has little time left, why make it miserable? Create good memories, do things you enjoy. She'll know how you feel even if you don't cry in front of her and I don't think she wants you to suffer. No mother does.