Just wondering if anybody else has been in a situation like this, I'm open to advice and criticism. I do feel like I screwed up.

I met Nancy in university about 9 years ago, became friends and supported eachother through a difficult program. While I did think she was attractive, I didn't think of her romanticly or sexually. After university we did have a harder time keeping up, Nancy deleted her social media which didn't help. We pretty much lost contact after the plague as we both work in healthcare.

I met my current partner, Paula, earlier this year who has been dating Conner for over a decade. While Paula and I started off as casual we developed into something much more serious. I now consider Paula my primary.

I recently got back into contact with Nancy who popped up again on social media. We reconnected and after chatting for a bit she came over. We were talking about life Nancy brought up a recent breakup (not Conner) that was pretty messy. The guy was neglectful and went around telling people she was crazy. While I didn't plan on anything one thing led to another and eventually we ended up in my bed. I was very forthcoming about being NM and my partner before anything happened and she was okay with that.

I was telling Paula about this the next time I saw her. I didn't notice it at the time but her demeanor changed when I mentioned Nancy's name, she started digging and eventually revealed that Nancy and Conner dated throughout high-school, that Nancy is 'crazy' and that if I continued to see her that she would have to break up with me. Paula has never said anything like that to me before.

I have spoken to Conner about this since (we get along very well), he doesn't think any less of me for it and even accused Nancy of seducing or preying on me (I corrected him). He doesn't think highly of Nancy but does think Paula is overreacting.