Generally, in this situation, both men and women say they'd like to know. But once the other party knows you cheated, the relationship, the majority of the time, ends in mistrust.
They say, what you don't know can't hurt you and it is true. If the other party never finds out, it will never hurt them. They can live in peace/ignorant bliss.
All I know is if you do tell, your relationship is over the majority of the time. You can guarantee she'll use this in EVERY argument, and when she almost inevitably cheats (because once one party cheats the other party almost feels entitled to it), you can guarantee she'll bring this up. All of my friends when they cheated or their GF cheated, had it brought full circle. Either that, or if they cheat, tell and are forgiven, they cheat again because well, they've already been forgiven once.
More likely than not, if you're a guy, you have a higher chance of the girl claiming that you sexual assaulted them and who are people going to believe?
Thread: i cheated, should i tell her?