Mike, do you two have any children? How long have you been married? Consider creating an autosignature that contains your pertinent details (see mine as an example) -- it will help others reply to you with on-point advice.
Let me ask you two key questions before I respond more fully to you:
1. Have you TOLD your wife that "I will not live in an open marriage" (I'm talking since she re-established contact with OM) . . . does she know this is a core deal-breaker for you?
2. Does she know that you know? (that she's back in contact)
I would urge you to proceed under the assumption that this IS a full-blown physical affair at this point, as it's highly likely.
I'm sorry you're here . . . as someone who went thru this myself, 8 years ago, I know how intensely painful and difficult it is.
