Definitely keep the chat logs and any other physical proof he may leave. You know it's one thing if your kid opens a door on you and catches you getting out of the shower. It's sexual abuse if you stand there and point your body parts out. That web site that was recommened to you, send that to him so he could see it himself? If he stays in the childs life I would definitely get a nanny cam. Even if you supervise him, they'll be times you need to leave the room.