I hate to say it, but I think you're being naive, Khold. The odds that it's not him are pretty slim. Even more slim that it would be someone else you know that shares the same IP.
It's sad, but even people one thinks they can trust can deceive him or her.
He possibly did it as a joke, but who knows? Unless he explains himself. As PL said, he hasn't responded yet. He's probably thinking "uh oh...crud," and is too embarrassed to admit anything.
Max, it's probably better now that you confess, at least to Khold, before this turns into even more of an episode. If you're worried about being banned, or something, you won't, as long as you stop with the emails to her.