I think I stole a cat.
How did you manage to steal a cat? Any idea who it belongs to?
I don't know, it was in the street but it had a collar on.
If the cat had a collar it also has an owner. It's not your cat to to take, you should have just left it alone. Now you have to find out who it belongs to and give it back.
Why would I return that piece of shit.
You obviously don't like it so you should let it back outside. You can even take it to a vet and they can scan it for a microchip and call its owners to come pick it up.