Very sad news. My sympathies.
The one cat I put down a year and half ago was a link to lost times, not all good, but places and people I'll never see again. I took her across country with me when I moved. I still remember her poking her head out the blinds of a second story Econo-Lodge motel room. I'd gone to get something to eat...I didn't tell the clerk I had a cat with me, but no one noticed. Heh.