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?
Assuming OP was right, I'd frame it more as his having an obligation to the husband as a human being making the choice correct rather than as a lack of obligation to the wife making the choice indifferent. We should be trying to make the world better, not carefully demarcating the bounds of social contracts so we can find out exactly where we're allowed to do as much harm as we feel like.
But I also think SadArtemis is right that OP, to put it charitably, got ahead of himself