If you found out that your significant other cheated on you, don't immediately rush to her and make a huge scandal. Think about whether you want to establish and keep relationship with your partner, or you will not be able to forgive her. If you understand that you still love her and don't want to lose, vengeance is better to refuse, because then your relationship will be even worse. If you have no more feelings for the traitor, and you are to take revenge, wait until your anger has cooled down, after all revenge is a dish best served cold.
The first thing you can think of as of revenge - to tell the girl about what you know about her betrayal, but it's not cause you have absolutely no emotions and feelings, as love to the lady you have not experienced, and just spend time with her, because she is so available and, like, not so unattractive. Most likely, after these your words, she will begin to tell you that you, too, she did not want that, she just used you, her lover much better than you in everything. Resolve a outlet for her negativity with a smile on my face, believe me, this is really gonna hurt her feelings.
The second method consists in the following. You can tell the girl that you forgive her, that your relationship remains the same, however, after some time, try to seduce her closest friend. For the girl who once betrayed you, this will be a very painful and sad, because she once hurt only you, and she hurt not only her beloved young man, but also closest friend. From now on, the cheater will need to find themselves and new boyfriend and new girlfriend.
Another way revenge is. You can inform the fairer sex that I recently visited a venereologist, and the results, unfortunately, were disappointing. You sick with something, and since has never changed its second half, so the carrier of the infection was exactly it. Of course, your lies soon you will still come out, but imagine that it will have the wrong girl, going round the local hospital and waiting for test results. In addition, it is possible that during these visits she met in the hospital someone from friends, who then love to tell everyone around that saw this girl in an intimate doctor. After that she is unlikely to escape a hideous sense of shame and disgrace.