How do you win a mans heart back when someone has told a lie to him about you?

Unfortunately this is not an easy task and if it is a lie and he chose to believe it then that tells me he does not have that much faith in you and it really may not be worth it. He should have listened to your side and if he wanted to be with you the same he would have believed you.

It may be time to move on and find someone that will return the feelings you are willing to give.