Bardog, stepping thru a minefield not of his own making...
I assume you have no intention of letting this thing start up again...so tell the wife what happened, in a way that lets her know that you have no interest in the ex, you don't want her to find out later & wonder why you were covering this up! As for the ex, we can't know her intentions til she lays her cards on the table, but my advice is soon as she does, nip it in bud, & don't let her damage your current relationship!

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If the theory does not conform to the facts, then the facts must be discarded.

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Never argue with an idiot. He'll drag you down to his level, & beat you with experience.