See, that's the problem; every situation is different. Off the top, it seemed that this was a case of the generic high school he-said-she-said, which is what I addressed. In that case, just not caring really does work, because as long as you set the facts straight with the third party--the lied-to's--then you've done about all you can without having to resort to bringing other parties into the mess. Been there, done that. And to be frank, neither were really worth being friends anyway, if they're the kind of people that tell and believe outrageous lies in the first place. Would a real friend believe an outrageous lie? I know my real friends wouldn't.
And it all really involves how extreme the backtalk really is: if its just the usual catting, then that's not nearly as bad as if they're libeling you and making up things that could be potentially harmful to you in a legal manner, like you are committing crimes, threatening people, etc. You get the idea...that's what I meant. I figured that if this was already serious legal issue, youd be talking to the cops and not people on the internet.
Here's my question for you: why do you associate with these people if you know that they always do this kind of thing?