My mentor is flawed. Now what?

Understand that people are people and that most of the time the human side of us wins more often than not. This is not to excuse his behavior because obviously he has some major apologizing to do and not only to his family. He has to fess up to all who watched him and looked up to him, that includes you. He is a leader of sorts and with that comes responsibility. You can still be his friend and he can be your mentor, but your view of him might be skewed for a while until he earns the trust that he has so blatantly given away for a 17 year-old girl.