The main thing - do not attempt to dot the i. It is not always necessary to reveal to man the truth about how bad he is and stuff. Each person has their own truth, and no one wants to admit mistakes for themselves, and successfully lays the blame on others. But because an open conversation will lead to the scandal, the waste of nerves and further confrontation. Moreover, it is not necessary to arrange "open separation" with those who often have to face, such as at work or in a circle of mutual friends.
The most reliable way to smoothly make communication. Time is something that every person is always not enough. For it is to rest: "I would be happy to meet, but I have a lot going on today..." communication gradually Reduce, and occasionally show signs of attention, but keep your distance.
Refrain from accusations and insults. Try to see in person and a good hand. Think about the reasons for his bad behavior. Go to Church and pray for his good health. Don't wish him bad. Don't say "he disappeared", replace the wording on the positive, "let him disappear from my life for the benefit of themselves and me."
Try to understand what life lesson you should learn from communication with unpleasant person. As a rule, when you realize your mistake and begin to understand the whole situation, a bad man as the magic disappears from your life. And no one like him, too, no longer appears. After all, mission accomplished. Lesson learned.