Yeah, I lost a grandmother to cancer. It hurts for awhile, and it should hurt, but it may not start hurting right away. Don't feel bad about that, it's natural. Don't let anyone else make you feel bad about that either.
First off, if you see the body, be prepared for the sight. It's not pleasant, but at least it's familiar. My grandmother was pretty sick at the end and looked like a shadow of her former self. They always look better after the morticians do their thing though, so at least the wake won't be traumatic.
Be prepared to comfort family members. Many will be glad for it, and it may help you feel better too.
If you can help anyone with a menial chore...and there will be some, like moving stuff out of her hospital room...then do it. Well, if you're up to it. It'll usually help you feel useful at a minimum, and they'll always appreciate an extra pair of hands. Well, they may turn you down and say "that's ok, we can handle it", so don't feel bad about it. At least you offered.
Of course, I knew it was a terminal illness from the start, and my grandmother passed suddenly after being sick for awhile, so your experience will definitely vary. Still, be there for your family. They're going to be having just as hard a time of it as you are, and by helping them, you help yourself feel better too.
