Your version of events as opposed to his (which obviously I've not heard). Maybe, he'll drop by and 'fess up to everything. Maybe he'd say something totally different on the other hand. Maybe you're in it together (even).
So, it's hard for anyone to really know what happened without more evidence and hearing both sides of the story. If everything is exactly as you say it is, move on and pick your friends more carefully in the future? It does sound like a horribly naive thing for you to have done - letting him keep the keys if that is indeed what happened. But I guess people like that do actually exist.
The world's full of shitbags though so if you don't want to keep getting mugged off, you're going to have to wisen up. Sooner or later.
Once more, good luck.
RE: This is such BS.... why are some people just out to get you and screw up your life?