I'm actually with this guy. Take it to the grave and don't do it again. What has been done cannot be undone. Telling her will only cause her a lot of pain. Everyone makes mistakes, learn from it and move on. It wasn't nearly as bad as it could have been. If you and your wife truly have a good relationship, and you DO love her, telling her will only tarnish what you have forever, even if you are forgiven. Then again, this advice is useless if you think there is any chance of her finding out via other means. If she is going to find out, better it be from you. If you are confident that she never will, keep it to yourself. Grow from it. I've been with mine for 8 years in January. When we were together for less than a year when she admitted to kissing another guy at some party. Happening back then is a lot different than if it happened now, but I still wish she had never told me. I never would have known, our relationship would still be as great as it is now, without that slight pang of "Hey that happened". I am more upset at the fact that she couldn't keep it to herself than I am that it happened. In retrospect it's not nearly as big a deal (again, different situation than you, less than a year vs 13, so I"m not comparing them 100%) as I felt like it was when it happened back then. I laugh about it now. Whatever life goes on. If you love her, and she loves you, there is nothing positive that can come from her knowing. It'll put a huge dent in your relationship regardless of how she handles it. Everyone makes mistakes.