Did you tell him and then both worked and reconciled or is part of what you are feeling guilt that maybe you haven’t been punished or feel like he can find better because your a terrible person.

You can be a good person and make a dumb choice. As long as you didn’t do it intentionally to hurt someone and you do carry guilt and a need to change oneself and fix the relationship and it’s a desire to strive to do better for yourself and your special person then no you are not a bad person. Martian Luther king was rumored to have cheated yet he was never branded a bad person. He made a bad choice because he is human and made plenty of other great choices because he strived to be better.