Couple months ago I met a woman who works at a dispensary I visit about once a week. We hit it off really well. Despite trying to just keep it casual sex, and that only, I ended up developing some feelings for her. She confessed the same to me. I even introduced her to my teenaged daughter, for fucks sake.
I ran into her this evening at a gas station, with another guy, who turns out to be her husband. They’ve been married five years, and have two children together, ages 4 and 2. Finding out they have kids just made me feel disgusting.
So, I told him. He didnt believe me until I described a tattoo in a somewhat intimate place on her body. I had no fucking clue she was married. I think I ruined someone’s marriage. Or at least took part in ruining one.
I feel guilty. I am sorry for what I participated in. Am I a bad person?
Talking about this in terms of social contract theory is really sidestepping the morality of the issue. Would you say that her lying entitles OP to punch her in the face? Surely not, two wrongs don't make a right, punitive justice is bad, etc. What OP should do is investigate the issue with her not because she "gets to" tell her side or has a right to, but because he doesn't know what the consequences of telling the husband would be. For all he knows, the husband is abusive and would beat her for this transgression, transgression though it is. The most likely outcome is, of course, that the husband is not abusive, but the most likely outcome of a round of Russian roulette is that you go unharmed. In either case, there is a real risk that is severe enough that it's worth checking, even if it's substantially less likely.