Wife in open marriage is now having sex with group asshole

Some background on us, I(36) have a beautiful curvy wife named Sarah(38) and we are in an open relationship. I love Sarah, shes a very sexually adventurous partner, with a lot of past fun history, me not so much. She had a lot of great past female sexual partners, some that we have played with together since.

She had mostly great taste but if there was one man that I couldn’t stand it was my wife’s ex-boyfriend, Tom. Tom was arrogant, rude, womanizer, and total asshole. We all went to college together and they dated for a year on and off, but we we’re in the same friend group, I was 2 years younger then both of them. And he always alpha male’d me.

At a recent mutual friends birthday party, Tom found himself unable to keep his hands to himself. He kept sneaking up behind my wife and touching her inappropriately, making it very uncomfortable by doing it in front of myself and the other guests.
I saw his hand was resting on her ass as we talked in the kitchen and I did my best to try not to notice, while being annoyed at Sarah for not pushing him away more. Finally, I had had enough after multiple obvious gropes, I confronted him after he started to drift his hand to her inner thigh. I grabbed him and said to come with me, I told him in no uncertain terms that his behavior was unacceptable and that he needed to leave the party immediately. Tom was taken aback and at this point I realised how incredibly hammered he was, he knew deep down that he had been in the wrong and was too drunk to put up a fight, so he agreed only if id be paying for his uber home. As he was leaving he looked at me and said, that Sarah of yours is quite the piece of ass eh! I remember back in that college dorm of all those times… She really could never get enough in those days. I was pissed but decided to put it behind me and get drunk.
A few months pass since that incident and Sarah tells me out of nowhere out of guilt that she had been secretly talking with Tom behind my back and they have been meeting up. We have always approved of each others playmates before hand. I was devastated and didn’t know what to say, she had been doing it behind my back because she knows I never would have agreed. She refused to stop seeing Tom, and said he is the only one who makes her cum properly and that she has been going to the club with him and having threesomes with other women together. I was heartbroken, but he couldn’t help but get aroused at that. I made her tell me the details, it turns out they have been going out every tuesday to a club. She told me she was spending nights with her girlfriends to mix it up, it was a lie each time she was going out drinking with Tom and getting in threesomes with other women..and having her brains fucked out by Tom every week.
Despite my dislike for Tom, I couldn’t deny that my wife was a strong and intelligent woman who knew what she wanted and she is going to do as she wishes either way. I realized that I dont wish to be the one holding her back and decided to let her make her own choices. In the end, Sarah is still in love with me, but our relationship was forever changed. Tom now takes her on vacation as well as uses her at his will at my house. I regularly walk in on him fucking my wife as well as another wife of one of the guys in our old college gang. I feel bad about our other friend not knowing Tom is fucking his wife regularly alongside mine, I don’t have the stomach to tell him. He thinks his wife is in a wine club with mine, so she can have an excuse after getting drunk at the bar and passing out at home.