My Boss told a fellow employee that I slept with his wife.

This may seem like an odd situation. My Manager(boss) told a fellow employee that I slept with his wife( x wife or seperated)He based this on the fact that we where at the same place at the same time. I've known them both for quite a long time. The person informed me that he had been told this by him. Not only did it not happen and never will happen, I have a witness that knows it didn't happen because they where there and they slept with her. I am a happily married man and hope to remain that way. I can only imagine what would have happened if my wife where to have heard this harmful rumor before I had told her the situation. I took the situation to my supervisor and he informed me that he had heard the rumor. I am now left wondering how many people think I cheated on my wife and everyday I go back I feel embarrassed and angry.

What can I do?

Thankyou