Thank you all very much for the help and words.
Frenchy, it was certainly NOT neglect. We had NO idea he had something wrong with him. This is the first time we've ever dealt with something like this. He went to yearly vet checkups and was diagnosed as fine every time. He didn't start losing weight until after his last appointment. He's had yearly appointments since the day I got him. So do NOT accuse me of neglecting my cat. And I didn't know this website existed. Sure it may be "too little too late", but I'm trying to get closure. And you're certainly not helping. Go eff yourself. I will definitely not be returning to this website.