It was actually a girlfriend of mine. We were friends for several months after breaking up. After a while, I noticed her friends and our mutual friends seemed really uncomfortable and furtive around me. I figured they were just having difficulty adjusting to the idea that her and I weren't a couple anymore.

Then, after an emergency, I wound up spending time alone with one of those friends. She noted that I "wasn't what she thought," and I asked her what she meant. She retold a story my girlfriend had told her about one of our arguments.

Except it was all bullshit. My girlfriend omitted everything she did (including threatening suicide), exaggerated my behavior, and outright lied at certain points. I gave the friend my side of the story and her response was "that actually makes more sense."

After that, I came to find out that my girlfriend had been spreading lies to all of her friends, including our mutual friends after the break-up. She'd portrayed me as controlling and abusive (this is despite the fact that we broke up because she was abusive, sometimes physically), and due to how integrated our social circles were, I wound up socially isolated.

Now that the lies are coming to the surface, however, things are starting to get improved. I'm probably gonna need some therapy to repair the damage done, but things are looking up.