(32F) found out (31M) husband sexted another woman years ago when we were in LDR

I am posting from a throwaway account for anonymity.

I (32F) married my husband (31M) six months ago. We dated for five years before getting married. This discovery happened now, over 4 years after the original incident and after our marriage.

During COVID, we were in a long-distance relationship while I spent a year studying abroad. We had agreed to be fully transparent if either of us wanted something else during that time. Recently, I discovered in his deleted Instagram messages that he had been sexting another woman during that period. Apparently, Instagram search history can reveal deleted messages.

When I confronted him, he first tried to gaslight me, then admitted it was wrong and said he was seeking validation. He told me he felt neglected while I was away, something I have always felt guilty about, but he admitted it was not an excuse. He also hid conversations with female colleagues, even if innocent, because he feared my reaction.

When I returned in 2021, he acted supportive and even unfollowed certain Instagram accounts I found questionable. I blamed my instincts for being paranoid, but now I realize he was hiding something he knew I would consider cheating. I love him and have been fully transparent throughout so I feel disrespected and cheated even though it is old history. I would have walked away in 2021 if he told me.

He claims he has been fully committed since 2021. I am struggling with how to trust him again, especially worrying about what might happen in the future if I cannot give him as much attention, for example during a pregnancy.

I don't know how to deal with this. I know it is years ago and it shouldn't matter but it is a foundational part of how I got into a relationship with him. In fact when our LDR became middle distance we spent a lot of time together and I asked him several times if anything happened during the time and that I would understand if it did.

I need help on how to move on from this. A part of me wishes I never found out as otherwise he does make me extremely happy. He only admitted and confronted it because I found out.

TL;DR: (32F) found out (31M) husband sexted another woman while we were in LDR during my study abroad. He confessed but hid it for years. In addition, he continued to have flirty conversations acting as if he was single for a year after LDR ended. I am looking for ways to rebuild trust and determine how to move on in a healthy way