My ex-friends step dad has been telling people things about mee!! what do i do?

My ex best friend fell out with me because i cut myself and she was calling me pathetic and childish and attention seeking but i cant help it because i have depression and bipolar.. her step dad has been telling my new best friends mum how very "pathetic" and "childish" and "very naughty" and a stirrer and how i jump from 1 friend to another when this isn't true!! i don't ow what to do because don't wanna loose my best friend or have her mum and dad hate me...!!!! help me!!