What to do when you're cheated on?

I was just a child (probably 7 or 8) when I first heard grown ups discussing something about cheating. I immediately decided that if a husband cheats on you, you should cheat back. That seemed very fair to me. Grown ups made me shut up right away. Why? Because if a man cheats it's ok, but if a woman cheats, she's a whore. So she should just give her husband an evil eye and that's it, they should go on being "a family". Oh and no divorce of course.
In my country most people still believe that men are superior. Men are allowed to have sex before marriage, while women should stay virgins until they get married (even if that happens when they're 40).
Not being able to have sex with your crush makes you desire him/her even more right? So that causes early marriages. Then they have kids right away (as I said in one of the previous posts). By the time they have a baby they have already satisfied their sexual needs and are not interested in each other anymore. A guy goes cheating (with whores mostly and sadly) while girl stays home taking care of the kid, because girl can't cheat right? And no divorce of course, they have a kid, how can they divorce. And that seems normal to most of the people, because it is believed that men want sex more than women.
Another thing is that with all the virginity and stuff men should be able to make the best sexual partners out of their wives right? No! You can't use your wife as a sex toy, you love her! Whores are made to be sex toys.
Sadly also girls who are not married and aren't virgins (or are divorced) are called whores too and many believe that they have to have sex with anyone who asks, because they're whores.
But back to the main topic - what is a woman supposed to do when she's cheated on? I still say - cheat back! If you don't stand for yourself, no one else will.