Universal algorithm for forgiveness lies there. Depending on the psycho man, remission can occur in different ways: some quite sincere repentance offending someone wants revenge, and some completely satisfy short-term separation from fraud.
Anyway, to let go of the situation, you have to try to understand what prompted the man to lie to you. Having considered and evaluated the reasons which led to the deception might just be much easier.
Then comes the stage of the adoption of the act - a fact uncovered lies, deception has already taken place. No matter how painful it may be to change nothing will not succeed.
Take a break from the experiences gradually unpleasant incident will be erased from memory and the passage of time will not seem so significant and serious. If you plan to keep the relationship with the deceived person will have to forget about his lies and even thought not to return to it.
Your restraint and generosity and will be a manifestation of wisdom. If you manage to erase from memory misdemeanor, you learn not to reproach this person in the future. Caught in a lie certainly feels remorse and is likely to repent of their deeds, to ask your forgiveness. The constant accusations and humiliation once lied can finally spoil relations, so are on the verge of breaking. So either completely forgiving iniquity, or put an end to the conversation. Medium can not be here.