One of the things my vet said that was super helpful when I was trying to figure out when to put my 15.5-year-old dog down was "don't let it get to the point where you feel resentment toward him for doing things that are beyond his control."

I keep in mind that animals don't seem to perceive time and end of life the way we do; they live in the moment and don't anticipate/dread dying from an illness. If they're miserable and have no chance of getting better, it's probably time to let them go.

It sounds like it's time to let your kitty go. I send my best supportive juju to you in this difficult time.