If his friend did tell him lies, and he didn't feel like he could tell what kind of person you really were enough to at least question it, or didn't want to ask you about it himself - then he's not the right guy for you.
He took his friends' word over your entire relationship, he doesn't have enough respect to talk about it with you first even... Not a good sign. Unfortunately if that's the case, there is literally nothing you can do or say to change things. It will only make you look worse and more guilty, so do whatever you can to move on. Sorry... it's so unfair but that's humans.