I’m the other woman?

I just had an ex-boyfriends wife reach out me. We have been apart for 6 years... I guess they have been married for 8. Apparently she had just found out about her husbands infidelity and is reaching out to all the girls to find out if it’s true and connect all the dots before she confronts him... I feel awful. I had no idea he was married! I ended up breaking up with him after 5 months because he was always on his phone and would be available and unavailable at weird times... i had a feeling I wasn’t the only one he was seeing but I was young and innocent and let it go on too long. Now I just feel like a home wrecker! I apologized to her and told her what she wanted to know, but I know her marriage is ruined if he has been doing this for 8 years. Has anyone ever found out they were with a guy that was married or even with someone else? How do you make yourself feel less stupid? I am happily married now and we are expecting our first child very soon. I told my husband about and he just kinda blew it off as it’s in the past nothing we can do about it... I love him for not freaking out on me, but I just can’t seem to brush it off so easily.