Like you, UP, I had some terrible regrets after my cat died (8 years ago!) I still think that I could have noticed the signs earlier. The vet misdiagnosed and prolonged his suffering. In retrospect I would have asked the vet to put him to sleep much sooner. It still upsets me to think about it, even after all these years, and until recently I couldn't face the thought of having another pet.
Over the last few months though I have thought that we could give a rescue animal a nice home, so perhaps we might take the plunge again.
It's still raining here. I ought to be cleaning the house but I can't seem to get on it yet. I've been tinkering with the piano, trying to learn a new piece, but it's not been very successful.
Time to get the Hoover out.