I'm sorry to hear about your kitty cat. It's so sad when they leave at any time, let alone when so young.
I just finished reading "Marley & Me" in preparation for the movie. I had put it off for 2+ years because I knew there would be sad parts at the end. Not just because of Marley but projecting the same thoughts on my petties, past and present. It was an 11-Kleenex finish for me so I figure I'll need a whole box in the theater.
Remember all the good times, and when the time is right, more new friends are waiting at your local shelter for love and affection, given and shared.