I've had my one cat 6M for 3 years and 1 year ago I adopted another cat 3M. They were best friends for the last 8 months. Out of nowhere, they started fighting. At first, I couldn't tell who it was, but I feel like it's my 6M cat attacking my 3M cat and I have no idea why. I started separating them while I'm at work, I've gotten feliway, I've tried calming treats, I've taken the 6M to the vet and they said nothing is wrong with him. Since they started fighting 3 months ago I keep them separated when I am not home most of the time.. I've been trying to allow them more freedom to be out together all the time again.

Today, I came home, and my 3M cat was brutally attacked. He has gashes all over. He peed himself, he defecated on himself. He's been shitting and peeing under my bed apparently. He was shaking when I came home.

I'm devasted. I don't want to get rid of either cat but my 6M cat is just too aggressive. He also attacked my arm when I was trying to break up a fight a few months ago and I needed to go to the hospital. Do I put my older cat on Prozac and xanax? Would a vet do that? I really would hate for him to get rehomed, but I'm exhausted, and I don't want my other cat to get killed obviously. Please help.