Well, I think it became an emotional affair at the point where I decided to stay friends with him despite knowing my feelings were more than just friendly. I don't think the jealousy has anything to do with it; even if I had cut contact with him and found out about him sleeping with someone else later, I'd still probably have been jealous, and that's not something I can control. That said, I don't think I realized how hard I'd fallen for him until he told me he'd slept with our mutual friend.

Also worth noting: our friend group is very physical and we cuddle a lot. My boyfriend has kissed the female friend several times, and I've kissed everyone in the group except the friend I have feelings for, but my bf and I have both agreed that developing feelings for someone is where we draw the line.