Yes, it's quite sad too because she got so old that she became deaf, blind, and crippled. Still, 23 is a good age. I'm not even that old yet! But I do hope I live a little longer, haha.
May have been feline leukemia. I had one when I was a kid who I loved dearly and that's what eventually killed her. Poor kitty. But she lived to be 12 years old! My mom had one when she was little that lived to be 23!