Jill - First: it doesn't MATTER if it was a physical affair or not, the betrayal is about the emotions anyway, so just let it go. Doesn't change a thing.
Second: old friend is WHACKED and I'd stay absolutely as far from him as possible. This is NOT how a friend behaves. And I believe it IS inappropriate to have friends of the opposite sex unless they are also friends with you as a couple - just bad policy, as you and H have learned.
Third: Tell H all about it AND about the email from OW, make sure he knows you did nothing to encourage this guy and find his behavior disturbing. Can lead to a healthy discussion about how NOBODY of the opposite sex should be in your lives who can't be invited to the dinner table with both of you.
