Calm down and think about the situation. Try to understand, if you really want to punish your lover , or simply are at the mercy of emotions. Imagine that you have already done it. Do you feel joy and satisfaction? If you have doubts about the reasonableness of their own actions, put aside the plans for revenge in the future: maybe after some time you will not want to even think about this person. Consider also your personal degree of guilt around what happened. If man took advantage of you, hiding your civil status, your indignation can be understood. But if you purposefully had an affair with a married man or they are married, try to start to understand themselves and their actions.
Plan their actions. Consider all of the potential results of his "revenge." Try to choose an option where no one gets hurt, especially small children. For example, if you tell the wife your lover the whole truth in this situation will suffer, rather, she herself, not "the hero of the novel".
Play on the weaknesses of your lover, as you have to know it well. For example, if it differed frugality, it will provoke serious waste. To blackmail and damage to property, of course, is not. Cunning and careful planning will help you empty the purse of the former is more elegant.
Ruin the reputation of men. Sent to colleagues, intimate photos, profile in his name wound up on a Dating site, bogus calls from a venereologic clinic: in good fantasy options can be a lot. However, think again if this is all you.
Get ex lover to regret that he lost you. Change the style, will buy a lot of beautiful things, do a professional photo shoot and put the photos in a social network. Get a new man, interesting Hobbies, travel. When a chance meeting with a former lover probably will experience a feeling of regret that you're not together. And you, in turn, can enjoy a new life and even forget about the recent plans to punish lover.