Your story concerned me, I too wondered if it was deliberate? I am so happy to hear you took him to the vet, I had a feeling it was not going to heal on its own. I understand how difficult it can be to pay for vet visits I have had to get help from rescue agencies ,loans from friends,what ever it took to help my cats!! Sounds like you found yourself a very understanding vet, please keep us informed about "kitty's" poor little tail.