I'm sorry that you are hurting and having so much emotion over this. I used to believe that I was just an emotional person reacting to external stimuli and that I had no control over those emotions. I have come to learn that my emotions are only biological responses to my own thoughts. Which means I am the one who kept myself in hurt, anger, frustration, anxiety, etc. I have learned lots of ways to retrain my brain not to go down those cheeseless tunnels and no longer live with my amygdala on fire from all the fight or flight response going on. Let me tell you, it is very peaceful compared to what I felt before.
Has someone ever tried to talk you out of your feelings? Did it work? Probably not. That's the thing about cognitive dissonance, you are very likely only proving to her (and likely her family) how justified she was in her actions. We don't persuade people through these sorts of titillating details, we only show them that we are the kind of people who speak them. And, as KML said, the majority of these folks have families that go right along with them, even when they know all about the affair, even when they abandon kids, and do worse things. Knowing is likely not going to change how they feel about her, but it may change how they feel about you. Does it affect you in some way if the family believes her story? I don't know this for a fact, but I suspect that the families probably believe this stuff initially, but then begin to see all the little pieces that just don't add up.
Having these statements and emotions be reported back to her likely makes her feel good (who doesn't like to think of themselves as so wonderful that people just can't let go). It shows her that you are not detached. That you are not moving on with your life. Is that what you want her to believe? Do you want to be the guy who is out there telling everyone her business (and yours by extension)? Forget about her. Who do you want to be? While we all hurt and can make poor decisions from that hurt (and I sure made my share), what matters to me now is how I see myself. The choice is obviously yours and you can do what you believe you need to. But often writing a nice letter and then burning it is equally satisfying and allows you to preserve your dignity and not have regret down the line when you gain more control over your emotions.
Oft repeated, but worth revisiting, forgiveness is for you, not for her. It is not the same thing as accepting what she did or validating it. It simply means giving her a notice to vacate from your head. It allows all those thoughts and emotions to be put to rest. It allows you to focus your time and attention on the person who matters the most--YOU.
