I swore I wouldn't ever comment on these, but I think some insight will help.

Before I tell it, I'm not interested in the internet's speculation of what is true and what is not. I only have her word to go on, so here is her story.

My serious (at this point long distance) girlfriend of a few years was out with friends, and started similarly "harmlessly" flirting with a a group of guys. One particular guy and her exchanged numbers soon after meeting for "innocent" reasons (he was going to give her an old sports jersey someday in the future). This went on until the bar closed, with him buying her drinks, etc. The bar closes, she is very drunk, and she and him stay outside the bar. He is obviously trying hard to take her home, and though she is enjoying the attention from an attractive man, the flirting, validation, etc, she won't leave with him. This outside of the bar conversation goes on for almost two hours. At this point, the sun is coming up and she decides to leave. Then the fateful moment, he convinces her to come with him back to his hotel and get the jersey now, as they will "never see each other again anyway." She gets in the cab with him. They walk to the lobby of the hotel and she "snaps out of it," like you claimed to before getting in his car. She quickly says goodbye, and gets a cab home. That is when our communication picks up, and she immediately lies about where she was and what she was doing, albeit drunk and frazzled. Within an hour, she has confessed to whole thing, and is devastated and confused as to why she did what she did, how she let it get that far etc. She would maintain for months that she never intended to do anything sexual with him, let's face it, one doesn't go to a hotel with a guy you met at a bar without entertaining the implications. Needless to say, not only did I not believe the facts of her story, but I didn't believe her lack of intent either.

Your husband sounds a lot like me, with an almost zero tolerance policy. Once she told me, I was beyond hurt. I didn't stick to my policy, and our relationship was forever changed. Trust was permanently damaged, and my confidence was shot. I was now the boyfriend of a girl that given the right circumstances, would go home with someone else. The dynamics of our relationship flipped, and we eventually split. She couldn't go out late alone with me wondering and fearing the worst. I would eventually hide it to make her think I was over it, but I couldn't sleep when she would go out.

When I look back at it, it still hurts.. but would things have been better if she never told me? I can't answer that. According to most comments in this thread, she "technically didn't do anything" or "stepped away from the ledge moments before jumping," and therefore, didn't REALLY do anything wrong. If you tell him, trust in you is damaged, confidence that you are "his woman" is dashed, and you are in for a long, rough road to recovery. You made a mistake, sounds like you've owned up to it.. but there will be consequences that you will need to face. If you want this to work with a man with such convictions, you WILL be questioned when you go out again. You WILL have to deal with comments about your trustworthiness. If you don't, you are lying to him and yourself. In a serious and honest relationship such as yours, an absence of a truth like that is just as bad. If it comes out later on in whatever way these things tend to work themselves out, you can expect the worst.