Thats the saddest thing that we have to face as Cat Lovers to know when its time to say goodbye.
I have had to do things with Several Found Cats , and the pain is so intense and you second guess yourself for a long time afterwards.
But you are right , no Animal wants to live in pain and discomfort especially if theres no real cure.
Now Montengros RVING it with the Animal Angel Army in Texas, and will find your very own place in the sun, where you can be friends again furrever.
One Fine Day.