Jim, i have had cats for many years, 2-3 house cats at the same time, they are wonderful pets. I have learned to think about the time I was so lucky to spend with each of them in this manner.

You the care taker have given your cat a safe and loving place to live its life. How great is that, how lucky was that cat to meet you, how great was it for you. Yes, it is very hard to have a 20 year friend and buddy depart from our lives. I feel this every time, the bummer of it never get easy.

On the bright side you can go and find another that will be great, have a whole new bag and different set of tricks to show you. Those crazy cats are just that way, spring is coming and that means kittens, just make sure you grab up another save it from a bad home bring it into yours.

I say this with the most sincerity and wish to lift your spirits some for now, only a new cat will make the recovery complete, best wishs and best of luck.
Greg