I personally haven't been cheated on, unless you count in grade 8 when my 'boyfriend' was grabbing another girls bum!
! ;D
In all seriousness though .. when I started going out with my boyfriend now, we sort of did this "If you cheat on me, just tell me." business. Now that we've been dating for awhile, if he did cheat on me, the potential for me killing him has gone up about 100 fold. Especially if the woman is 'lesser' than me (sort of how *Nikki* felt about that woman her ex-SO cheated on her with).
I honestly don't know what I'd do. Slash tires? I have a real mean streak sometimes.