Hi WSM,
One other thing if you don't mind, I have a suggestion for you that I learned about the hard way.
No matter what the reason for this lie, don't waste your time trying to convince him that what he said was untrue. He may cling to the lie even more tenaciously. It doesn't really matter what he says about you, or to whom he says it. You do not need to prove anything or save your reputation. People who really know you already know that's a lie or a delusion, or whatever. This is the truth: whatever he or anyone else thinks of you is none of your business. Don't get into a circular game of, "You lied about me." "No, I didn't." It'll go back and forth and the issue is not the lie but what is causing the lie. He will drag you down in self doubt and you'll start questioning everything you have done and will do, and you will cave to his whims to stop him from thinking badly about you because it's only natural for us to want our children's love and respect.
I have reached the point with my son that he's allowed to have his truth, and I mine. I don't waste one minute of my time on his false accusations and rip-roaring fabrications. He knows if he wants help it's available; if he wants to wallow in blindness, I am powerless to stop him. What I wish for him and what he wishes for himself are miles apart. Hang in there.