I'd say some humility is called for, but its hard with male pride. And I suspect stubborness. I believe he is basing things on believing you have been the deceiver. I just don't know why you even go there at this point.... You are a patient teacher of what you know, but he doesn't want to accept it and is trying to prove you wrong from a creationist viewpoint. He just doesn't have the expertise for this particular stuff...

If on the other hand you have been playing games, you should also own up to that, though.