Husband hugged a coworker and there was some sexual touching from both sides

My husband has known this coworker for a few years now. They are friendly and its a group of about 4 peers. My husband progressed to being a manager a few years ago. His friendship with this group was affecting his ability to be a good manager and he decided to move to a different team. He is still friendly with his old team.

This particular coworker always struck me as having a bit of a crush on my husband and vice-versa whenever we met at company events where the families were invited. Just a little harmless attraction as I viewed it. My husband isnt new to having female friends at work. I've known him a long time (15 years, 10 married with a much loved daughter) and have never suspected anything more than friendship with some of his female coworkers so this incident shook me.

Last week, he got to know that this coworker was quitting and is moving to a different city for work. He met her to get lunch. a week later he confides in me that he is feeling very bad about crossing boundaries. He says that him and this coworker hugged when saying goodbyes and there was sexual touching and they pulled off. It got awkward and that they decided its best they don't stay in touch. After he confessed, we spoke a bit about how i feel about this all. He accepted this was a horrible lapse of judgement and he should have done better.

I was extremely disappointed and felt dishonored. I know it could be worse but its the first time there has been a transgression of my boundaries here and he knows it. He is remorseful and i am glad he decided to be honest with me but it HURTS.

I want to ask this group how I can rebuild trust. I am not even sure why this is hurting me so much. I've cried all night and I am not sure when or how to get out of this. Our 10 year wedding anniversary is coming up in a few days. I really would appreciate some advice.