Sticky loan situation, what should I do to get my money back?

You are very wise yet not so. You are correct to be cautious before making a public statement about the debt as it could be slanderous. Instead I suggest sending him a letter via certified mail. If he is true to form, he will likely refuse receipt, but it would provide you the needed proof that you did your best to resolve the issue outside of court. That being said, you future law suit is likely going to be an uphill battle when it comes time to prove the money was actually a loan and not a gift. Good Luck, I think you are going to need it.