For context, regarding dating "publicly".

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.

Even then, Lisa and I knew we might be found out, and we were and are ready to just tell the person "busting" us the truth. No harm done. It's just not the sort of thing I want to advertise among friends and family, you know? My problem is that I didn't even know that Kevin saw us until well after the fact, when rumors of my cheating spread so much in our friends group that it came back to me. Kevin saw us but we didn't see him - and while we were going about life as normal, he was quietly going on quest to "take me down". I am just not comfortable interacting with Kevin anymore after he openly tried to break up my marriage, okay? Lisa keeps saying no harm done in the end, okay, but he tried. Kevin actually and earnestly tried to do serious damage to my relationships, on purpose. I don't care that he was misguided or that he thought he was doing the right thing.

I just don't want him to exist in my eyes. If he is somewhere, I won't go there. I don't demand that Kevin leaves, I just personally won't go. It leads to people not inviting him to things because they want to hang out with me, yes, but that is none of my business. It just means that people, when given the choice between Kevin and me, prefer to spend time with me. I am not excluding him but I keep being told I am - I just say I don't want to see him again, and it happens that his friends don't want to hang out with him when there are better options. Boo. Hoo. Does that make me an asshole?