I try not to lend money if I plan on seeing it again. People who need to borrow it often won't have the means to pay you back, and even people close to you can forget. Even so, it doesn't make it right, and it's disappointing when it happens.

No, you did nothing wrong. Not only did he take your money, he's making you feel guilty about wanting it back! He sounds like a "user," and may need a lesson more than you need the money back.