Dont let this guy get away with this. I know the feeling of the no sleep thing. You need to take care of this right away. Take someone with you and confront him. If he wont give it back beat his ass real good. It will be like lifting a cinder block off your chest. If you let this slide you will have other people fucking you over. Dont be known as a guy that can be ripped off. Make sure all your friends here about it. Give him a real good beating. This will never happen to you again. At least not from a friend.