I just saw this thread after the new posts today.
Sorry about the lost family member.
I can relate. A month ago I lost my first dog. It's really not easy, and it still feels very weird. He was a 12 year old yellow lab, who rebounded from a severe decline in red blood cells two years before his passing (purple tongue, gray skin, etc.) He was a fighter.
It's so hard to do the right thing. He couldn't walk anymore. He knew exactly who I was. He just laid there on the floor smiling and wagging his tail like always, and all I could do was tell him he wouldn't have to suffer anymore, and how I was sorry that we couldn't do anything more to help him.
P.S. Your cat is the origin for the picture in your avatar? I have seen that picture numerous times, and it's pretty popular across the internet. It's the first result for "smiling cat" and the fourth result for "smiling kitty" on images.google.com. As far as the internet goes, your cat would be considered legendary.