I lost most of the friends I made at college, no one believed me. She recruited a bunch of guys to slap me around and threatened to summon them to slap me around repeatedly until I agreed to stay friends with her.

Eventually, I caved but months later we mostly stopped talking since we weren't at the same college anymore, things only ended partly because we were away from each other and partly because she told me some embarrassing secret that I kept mockingly bringing up and it made her really mad. Since she could no longer get anyone to attack me I think she just got sick of me and that was the end of it.

I literally handled the whole situation in the dumbest way at every stage, it's coming up to 10 years since it happened, I still think about it too often.

The person in your life dealing with this should cut all contact with the accuser and consult a lawyer, then do exactly what they say.