Yikes, so sorry to hear about your cat's tail. I would find another vet for sure, but before that, I would medicate the cat so that he doesn't know what is happening until his tail heals and the hair has grown in a bit. I know it sounds horrible to knock him out, if you will, but it will put him out of his misery for awhile .... make sense? Maybe some Prozac?

Keep us posted.