I am so sorry for your loss and suggest to you to go in the cat memorial section and make a memorial for her. It will be there forever, for all to see.
You should tell the story of how you got her and somethings about her personality and what kind of cat she was, even post pictures if you have them. Celebrate her life in her memorial.

I haven't a clue as to what happened to her, I had a friend that recently lost his cat suddenly and don't have a clue as to that happened also.