A cat neuter is barely even a procedure. He should have been up and ready to go in less than 12 hours. The fact that you waited for 4 days to post a question like that on a gaming forum is showing that either your veterinarian didn't explain a single thing about recovery or that you're not fit enough to look after a stuffed animal, let alone a living animal. Do yourself a favor and ask a responsible friend to please take the cat so that way he doesn't die.