The lying, bitter ex: who is she?

Women, have you ever met a bitter ex-girlfriend who told egregious lies or unseemly truths about an ex-boyfriend with no chance for personal gain?

I ask because this is a common narrative, but I have yet to encounter such a person. I have certainly run into women with tales to tell about an ex, but usually these tales are told for reasons very distinct from besmearing the name of the perpetrator. Often, in fact, the perpetrator remains unnamed and can't be identified save for context.

Am I wrong? Tell your tales!