How do I handle this? Part One?

My wife and I both divorced cheating spouses. We hit it off quickly when we started dating so we agreed to an exclusive relationship and a commitment to eventual marriage. Sadly, during this time frame she cheated on me with a friend of her girlfriend, we broke up, went our separate ways, I started to date another woman, etc. She and her new boyfriend did not work out so she approached me about reconciliation and I agreed to start the process of “working things out”. Married a little over seven years now, this happened around ten years ago. Good times have been good, bad times have been bad and too frequent so it seems like we are constantly working things out. During the first “working things out” period she seemed more interested in what I had done instead of what she had done and insisted that both of us promise to never initiate or accept contact from the other “party” without letting each other know. I never saw my relationship exactly as she saw hers considering I never cheated but I wanted this to work so I agreed and never broke my promise. Shortly thereafter I found out she had talked to him concerning some “business”. This bothered me particularly since the promise was her idea, so I let her know it but life went on supposedly without more reasons to wonder if she was keeping her promise. Just a couple of years ago due to a slip of her tongue, I found out she (now as my wife) had been looking for some information concerning this guy on Facebook after all these years and after all we have gone through! This really set me back, I wondered what else I might not know about. Insecurity welled up inside me once again. I became very angry, wanting her to just get out of my life, go with this guy as a legitimate reason to end this marriage. She said her reason for doing this was to see what his wife looked like. Her apology at the time was I am sorry you are angry but I don’t agree that you should be. This was just a thoughtless act to her and I was overacting. Well maybe so but that just made it worse for me at the time. It also reminded me of the years I waited to receive an unconditional apology for the initial cheating episode. And to top this off, just before I found out about this Facebook thing, I had written her estranged friend (this person is the actual girlfriend mentioned above) to let her know I forgave my wife long ago for this and the matter is settled so please stop hling her about this. Is it rational to wonder if the estranged friend might know more about this than meets my eye?