I have been a money lender and agree you should contact and tell him. He probably already knows you are not going to pay him back because of your hiding. But, the hiding makes him think less of you; you are not a "friend" to him with your immature actions. You told us what happened, I would contact him and tell him, he's the one who matters, who cared about you in the first place enough to lend you the money. Care back and tell him what happened.