My fiancée slept with her ex-husband and I don’t know if I can (or should) get over it. We I met three years ago when she got hired at my place of business. Her husband was an acquaintance of mine, because he worked with me too. She was openly unhappy with her marriage, taking every opportunity to tell her friends about her husband’s shortcomings. Eventually, she separated from her husband, moved in with me and got divorced.

Her ex-husband began stalking her, and exhibited suicidal tendencies. She attempted to maintain a civil relationship, mostly because they had two children together, but also because she was worried he would actually kill himself. Soon after their divorce, they sold their house and separated their belongings. She became emotional about her failed marriage. This resulted in them sleeping together, even though she had already moved in with me. They slept together about six or eight more times over the next two months.

I didn’t know about any of this until several months later when her ex-husband told me about it. She initially lied, telling me that it only happened once on the day they separated their property. I slowly fed her more and more details of what I knew, and each time she lied about the extent of her affair with her ex-husband. Once she found out that I knew everything, she told me that the first two times were “what-if” encounters. She was upset about her failed marriage and wondered if she should work things out with him. The remaining encounters over the next two months were the result of pressure from her ex-husband. She told me that she slept with her ex-husband to keep him from telling me about what had happened. If she turned down his advances, he would tell her, “I wonder what your boyfriend would say.” Each time, she would tell him, “Ok, but this is the last time.” Her ex-husband confirmed this to me, but he did say that there was more emotion during sex than there had ever been during their marriage and that she even initiated some of the encounters.

I broke up with her upon discovering that they had slept together. She begged my forgiveness, and I eventually took her back. Our relationship seemed to grow stronger over the next several weeks, but I can’t seem to get over the mental images of them being together behind my back. She and her ex-husband now have very little contact. They don’t see each other at work because they work different shifts, and their child exchanges take place her mother’s house.

I love her, but I don’t know if I can trust her again, even though she takes every opportunity to show me how much she loves me and wants to be my wife. Should I leave her and cut my losses, or should I give it a chance?