If you’re talking about verifiable events that are being misrepresented, then eventually the falsehoods are going to be realized. But if you’re talking about falsehoods regarding things that are intrinsically unverifiable, then there’s nothing you can do.
If a person consents to listen to someone who is talking about you behind your back, that is because he wants to accept the gossiper’s judgement as truth.
If you attempt to correct the falsehoods, you cannot be heard, because once that person has absorbed the falsehoods as fact, he can only see and hear you through that filter. That means he won’t be capable of seeing you for who you are, only as the gossiper has chosen to present you. And because you can no longer be seen or heard, there is absolutely nothing you can do to change it.
There is simply no way to correct that kind of situation. You could sin through gossip or anger, but you still couldn’t correct it. Pray, pray, pray, pray, pray and lean very hard on Jesus.