Uhtred,
Your story sounds so very much like mine. The guy my XWW traded sex-for-flattery with was 52 and she is 34 - old enough to be her father. He is a worthless piece of shit who has a reputation for preying on and having sex with weak-minded, dysfunctional women - like my XWW. My marriage was good and I worked hard to support her and my two young children. I knew my wife had some self-esteem issues but thought her boundaries were very strong especially anything regarding her family. I was so very wrong.
The way your WW's affair began is fairly similar to the way mine did. I also knew him. He would look me in the eye, shake my hand, and talk to my children - all the while sleeping with my wife and my children's mother behind our backs. His, and her cowardice still stuns me to this day. I am ashamed that this is part of the cloth that my children are cut from. It is my mission to steer them away from the path she has taken in life.
I also had a confrontation with her affair guy and she was there too. I saw her car in his driveway and decided to confront - not as a husband, but strictly as a father. I wanted to and could have beaten this man down but I knew as I approached and started pounding on his door that if I did that I would end up in jail with assault charges, lose my job, and this coward probably would have filed a civil suit against me. I went there to tell both of them, on his turf, to their faces, that they were fucking cowards who have been hiding behind mine and my sons back for the last year. To tell her that she threw her family away and her children's foundation for a worthless piece of shit.
It took quite a while for someone to finally open the door. It was her with her tail between her legs telling me they were just talking and pleading with me to go. I kept pounding while yelling loudly for this coward to come out. Several minutes later he comes to the door and stays several feet inside from the entrance because he knew that I was not likely to rush into his house and assault him. He asked if I was there to fight him. I laughed and told him "No, I don't fight for shit that betrays me and my sons" as I looked at her. And actually, that was the truth. She was simply NOT worth a fight.
Now, here is my point.
You have to try and look at this from the warped perspective she has and understand it to get why fighting this guy was not a good thing. (Mind you, fuck him - he indeed deserved it. He would not want you to have done to him what he did to you and your family so again, fuck him.) your WW was seeking validation and self-worth from the attention of another man. She loved the attention and flattery so much that she was willing to risk losing everything for it.
For quite some time she was able to have her cake and eat it too. She had you at home, working to provide, and being a father to your kids, and she also had her secret responsibility-free, bullshit flattery-filled fantasy life with the adultery guy. She had two men that both wanted her - lots of feeling of validation.
But, that state of mind was based on the deceitful secret she had. Her fear was that if you found out her secret that you would leave her and end the marriage. Thus, losing a great part of that giving her stability and self-worth. When the secret became known instead of her fear being realized and her losing you - you rushed over to the adultery guys place and fought him. Now, in her mind she now has a sense that here were TWO men that were fighting OVER HER. That can actually be, in her twisted thinking, somewhat rewarding. She has not one, but two men vying for her affections. That's awfully validating to someone with those kinds of issues. In the end, what could happen is that going over there and beating the shit out of that asshole could have actually given her some tacit approval for committing adultery.
I wasn't going to give my XWW that satisfaction that I was fighting for her after she betrayed me in the ultimate way. Fuck that. She was initially remorseless and continued with the guy while saying nothing was going on. I filed for divorce. She came crying for reconciliation. I divorced her. She still wants to reconcile. I don't accept that shit in my life and my kids need to see that one deserves better, and can do better than that.
By the way, these events are all seemingly recent. Right now, I'm sure the adultery guy still has some sense of guilt over what he did but that may fade over the next few weeks or months especially as he continues to deal with his injuries and expenses incurred because of them. His guilt may turn to anger and you could still find yourself facing assault charges and a lawsuit filed against you for pain, suffering, medical expenses, etc. I'm sure there would be a small army of lawyers drooling to take his case. The fact that he was committing adultery with your wife would not be a defense in a court of law. Your wife was a willing participant so it could potentially be excluded from any defense.
I would consult an divorce attorney to find out your rights if you decide to divorce and also consult with another attorney specializing in defending a lawsuit like this potential one. They can tell you what you can do now to protect assets from a future lawsuit.