popintofnoreturn-
BS prespective here.
A few years ago (before meeting H), I ran into a guy I went to high school with. Shortly after running into him, he sent me a message on his facebook, telling me that he always found me attractive and wanted to go out sometime. I remember him being one of the cooler guys- I was flattered and took him up on his offer. We flirted via facebook for a bit, and eventually met up for dinner and drinks afterwards. We hooked up that night. We went out again a few more times, and hooked up (as in sex) all of those times.
Eventually, he admitted that he was in a relationship, and actually engaged. I was stunned- his facebook said that he was single, he had flat out told me he was single...I was an OW!! I found out that the facebook he messaged me with was an additional account that he used to pick up women. It was one of the most embarrassing moments of my life- I was so disgusted with myself.
You know what? We didn't go out long enough for me to see any signs that I should have. He lied to me multiple times, and that is not my fault. I told his fiance and he FLIPPED OUT, and accused me of ruining their relationship. Nope, I didn't. He did, when he chose to lie to me and use me and do the same to his fiance.
When my H cheated, it was online. None of the women he talked to had any idea that he was in a relationship. It either wasn't asked, or he said flat out that he was single. You know what? I don't blame those women at all. To me, it is completely different to have sex with someone knowing that they are in a relationship, and have sex with someone who you think is single.
I understand the wanting to know- but honestly, I would not break NC. He could have lied to you, and if he did, it really is not your fault. You did what you did with the information you had. Focus on your life now, who you are now, and your marriage now. Don't break NC, and don't stress about the "what if's." If he lied to you, it's 100% on him.
The fact that you are going back, reflecting on previous mistakes, and are concerned about who you may have hurt along the way shows how caring and empathetic you are, and shows that you are truly remorseful and have made some huge steps in changing. You are amazing!