ladypomegranate

There are some people who can function perfectly well in an "open marriage." But if your past ex having an EA upset you, I seriously doubt your relationship could survive another similar betrayal. It sounds to me like your husband doesn't really have that much respect for you and you should call him on that. Does he have any idea how he could hurt you (beyond the emotional pain)? He could transmit an STD to you, get another woman pregnant, the list goes on and on.

Unfortunately, you're kind of in between a rock and a hard place now. If you tell him no he's likely going to cheat anyway. He's already got the idea in his head and that's compromised his fidelity to you. If you tell him yes there is no coming back from that decision. You destroy all trust in the relationship.

I'd suggest therapy if he's willing. He needs to be told by a professional that cheating is cheating no matter how pretty you dress it up. If that doesn't work then who knows.

Of course, the advice you get on this forum is going to be tainted by what each poster views as a "normal" relationship, but just ask yourself: when you married him did you think that was a commitment from him that he would be yours and only yours from then on? If you did, then that should answer your question.