UPDATE: I was taken aback by the many thousands of comments and private messages I received, and I want to address a few points.

I've heard many... many many times that it's my fault for dating Natalie in public when the fact I'm poly is not openly known. Fair point. But, for context, I live in Ile-de-France - population 12 million people. Natalie lives in a completely different part of the city from Lisa and our friend group, and I think we were going to watch a movie at a cinema located in an area where neither me nor Natalie lived. Chances to stumble on someone we knew were basically 0. And me and Lisa were and are still fine with people knowing we're poly, I just find it very embarrassing and I'd rather not spread the word around. It's just not the stuff I want friends to know and tease me about. It's not as dire as being gay and in the closet. We faced no actual rejection when the info became public, I know we are privileged in that way.

The problem I have with Kevin is that he made up this fantasy in his head in which Lisa is a damsel in distress and I am the bad guy. Even now that he approached Lisa and she just told him she knows Natalie well. Poof, fantasy evaporated. But he was so dead set on demonizing me in the eyes of my friends that I don't think I WANT to forgive him. Lisa doesn't mind everyone knowing we're poly and talking about it with friends and relatives, she thinks Kevin didn't mean to do anything wrong. Which is easy for her to say when she was "the victim" in the eyes of everyone while I was being cast as "the villain".

So yeah. I'm not asking Lisa to stop talking to Kevin or what, but I don't want to ever see his rat face ever again.

I'm polyamorous. My wife, Lisa, has a boyfriend (Jeff) and I have a girlfriend (Natalie). The four of us hang out together, we're all consenting but I don't advertise that I'm anything other than traditional monogamous with my and Lisa's friends.

Enter Kevin, a not-so-close friend of Lisa's who happened to see me out with Natalie ~2 years ago. He assumed that I was cheating on my wife (fair) and tried to right that "wrong". If he'd just gone to Lisa and said it to her, she'd have clarified the misunderstanding, no harm done. Instead, he talked in private with several of my friends to "gather evidence" on me. Every time, he told our friends that I'm a cheater, low life, monster, etc - one friend was approached on Facebook messenger and screencapped Kevin's conversation. Kevin said, I quote: "Help me take down that f__ing bastard".

Then Kevin finally heard from Lisa that she approved of my relationship with Natalie, and I was forced to come out as poly publicly to shush the rumors I'm a dirtbag cheater. So, thanks Kevin.

I've been clear: If Kevin is invited anywhere, I'm not going. I still hate the guy's guts. I've been the butt of every joke and called a cuck a hundred times since everyone knows that my wife has a bf. Kevin demonstrated genuine hatred for me, I refuse to ever consider him a friend again, even though Lisa insists that Kevin "thought he was doing the right thing." I refuse to give the dude another chance. AITA?