Feelings for another man while married

Me and my husband have been married three years and dated three and a half before that. We got married very young, I was 19 he was 20. We have a beautiful son together. Well over the course of the time since we’ve been married I’ve slowly wondered if I made a mistake in marrying him. I stayed with him as a teenager and felt with things I never would now. We have always fought and he was talking to other women when we were dating and about 6 months ago I found out he was talking to other women on Kik. Since that happened I’ve been having a hard time trusting him and we’ve been fighting nonstop. I don’t even know what he said to the women because the app deleted the messages once I tried logging in on my phone, after I found an email buried with an alert from them. He says he was just lonely and that’s why he did it, but I’ve been increasingly unhappy since then and find myself wishing he’d do it again so I would have a reason to leave him, as messed up as that sounds. I want our family to stay whole for my son but I’m just so confused and tired of fighting. I had feelings for this guy in high school, we’ll call him Mat, and since this incident with my husband I can’t stop thinking of him and wishing I’d pursued a relationship with him instead of my husband back when I was younger. Mat told me how he felt when me and my husband first started dating and I had been so mad at Mat for being too late and ended up being loyal (to a fault) with my husband. Anyways, for years I have dreams about being with Mat romantically and I’ve fought them off for literally 6 years, but after what my husband did I feel they are controlling me and I think of Mat constantly. I feel so guilty but so confused. Any advise?