How far did it go? Did you have sex, just kiss, fool around? Why do you want to tell him? Just to come clean? If you honestly think he will leave you and it was a one time thing that happened years ago, I personally would keep it to myself. If it's just eating away at you and you can't take it anymore tell him but realize it could end your relationship. At the very least it will cause some serious trust issues between you two.

<blockquote><b>Quoting 3 little monsters:</b>" How far did it go? Did you have sex, just kiss, fool around? Why do you want to tell him? Just to come ... [snip!] ... him but realize it could end your relationship. At the very least it will cause some serious trust issues between you two. "</blockquote>

I had sex with another person.