I have a problem, so my ex best friend is being a rude cruel witch.

Well its a really long story but at the end we became worst enemies and now she's really getting on my last nerves, each facebook friend i have she adds and she post on their wall crap about me. I dont care for her anymore I mind my own business and she hates that. but lately she has been up to no good any suggestions on what i should do to her?