I DID SOMETHING BAD!!!!!!HELP PLZ?

This dude whose in my grade was bugging the crap out of me Wednesday so I took his binder and I kinda doused it with water and stuff so now its ruined. We had a binder check today and since he lost his binder he didn't get that many points. Well I didn't go to school yesterday and I guess he went and talked to the principle about somebody stealing his binder. Today they were questing people and stuff about it. Im scared cuz this kid likes to get the police involved and crap so will I go to jail? They have no proof it was me and the kid doesn't suspect me at all. Should I give it back? I only told a couple of people that i did it.