This large excerpt is from the following fantastic site:-
www.baggagereclaim.co.uk/understanding-why-an-ex-is-spreading-misinformation-about-you-or-building-a-case-against-you-to-break-up/
The person who sets you up or spreads untruths after a breakup wants to
Control who is in touch with you and in fact, sever ties. If they run the risk of you all talking and even comparing notes not just on your own relationship but their past ones, you (and they) will figure out what’s up. They want to preserve a certain image.
Stay deluded and avoid responsibility. Some people always give themselves and others very similar reasons for their breakups.
Save face. Some people overestimate their capacity for a relationship or oversell things and Future Fake. Rather than say, I talked out of my bottom a little too much and got carried away, it’s easier to generate a different ending to things. Unfortunately they don’t learn from the experience and so lack the self-awareness needed to see their actions for what they are.
Keep the harem intact. They may have a bunch of sycophants who value being in the lair so much, they’ll believe anything. If your ex is narcissistically inclined, they’ll be very charming and manipulative but they will also have harem members who will be too damn scared to rock the boat by questioning the claims.
Control you. They discard you, mess with your head, and next thing you know, you’re looking for validation from them and you’re at their disposal because you’ve inadvertently become complicit in their deception by still wanting them despite their shoddy behaviour.
People who don’t fabricate reasons to support their decision to break up – it’s making a decision back to front – or who don’t go around spinning stories so that they can make a fresh start and create a vacuum for their next target (while also ensuring that they avoid the truth about their actions as well as their own part in the relationship), cannot for the life of them fathom why somebody would do this.
Of course what you would do and what another would do – and that includes someone who you had romantic feelings for – are two very different things and that’s a kicker too. We don’t like to think that we loved someone who could be so immature, unkind, and even malicious.
As humans, we have a disposition to concern ourselves with what others think. It hurts when we do our best to be decent people, to love and care generously (sometimes too much so), only for that to be mistaken for weakness and treated like this bad thing that makes us tricky to offload. It makes us feel like fools (we’re not and their actions aren’t our fault either).
A good chunk of the pain felt is around that lack of control over what people think. We feel frustrated, angry and wounded because we don’t feel that we have a right of reply. Even if we speak up, it may just make the situation worse, after all, if these people have decided to believe this stuff, they may decide that us sticking up for ourselves is us trying to convince and convert.
You might be tempted to engage in some reputation management if you have mutual friends or if they’ve gone so far as to say things to your family or coworkers (beyond unacceptable) but you will potentially end up fighting to preserve your image of you with people who won’t matter to your world in a matter of months never mind years plus you will end up fighting to correct an image of a relationship that’s over. You will be trying to control the uncontrollable. The main image that you need to correct is of your ex. It doesn’t change that you enjoyed good times together but they have unfolded in a way that shows traits that don’t make them the loyal, loving, caring, respectful, trustworthy person that you deserve to be with. They’re showing you that it’s the right thing that you’ve broken up.
Some people will surprise you by being taken in by this crap and that will hurt but it’s best to know where you stand. Say your piece once if needed and then let the chips fall where they may. I do suggest however that if your ex is being particularly malicious, that you note any and all attempts to make contact with you (don’t tell them obviously) because it’s evidence of their lies and manipulations. But don’t devote too much time to them because you have a life to live…without them.
The best rebuttal in this situation is to live your life well instead of hiding away or devoting your life to defending and convincing this person or their homies (or cronies). It doesn’t mean that they’ve ‘gotten away with it’ – you cannot force feed your ex or their ‘audience’ the true version of events. Trust that their actions will manifest themselves in their lives in some way and go about your business, probably with your teeth gritted at first.