I'm so sorry to hear about your loss.
I lost all three of my childhood cats within a year. It was really hard on me because except for one I don't really remember life without them. I agree that your pets are family members and their deaths can require much greiving. I still get teary eyed when I think of my kitties... I miss them so much.
What we found surprising when my first cat died, is that another of cats (the mother actually) grieved for her. They had a place they would always sleep together and Kitty (yes yes, originality) would just stay there all the time - just waiting. We had to move her food down there for awhile because she just didn't want to come up - even to eat. She got over it after awhile. Ironically, she was much better when the other cat died, but I think that's because he was mean to Kitty and always bit her.