PROTECT her indirectly as a Husband should from predators, but do NOT purusue her outright.
Keep an eye on the OM, that affair bust was way too easy... I don't think its over yet.. keep VERY close tabs on that guy.
I had the same problem in my home, I was TOLD it was over, and I thought it was, so I got complacent, for three months they were runing around behind my back and lying to me... I felt like a complete idiot.