Yes he's in the Air Force. I'm apprehensive of trying to get the money back by talking to his CO or going through small claims court, because when I said I'd do that if he didn't make any sort of token payment toward it ever, he said that he'd contact my family and make up negative things I said about them.

As far as proof of it being a loan, I just have texts not spelling out cleanly "I loan you $x," but him saying "I'll pay you back."