Advice please i need some. Bullied. Sorry for long text. Iv shortned it at bottom

So there's this girl in my class we started of for friends. But I made another friend and she wasn't happy with that and basicly she's been a b**Ch of a friend she makes me cry and cry I come home crying she takes my things runs of with them then changes the story saying I toke it of her when i didn't and today I decided to stand up to myself as she toke my bag and ran of with it I ran after her she went into the bathrooms so I followed I grabbed my bag of her and told her in a firm voice don't talk to me again! (I sounded like a p***ed of drunk guy) she laughed pushed me to the wall and ran of dropping my bag on the floor. (Btw she cut her arm in sport class u will need to know this soon)

And then went home and said to her mum I asulted her saying I cut her, hit her, attacked her you name it and she has messaged me I'm reporting you to the police.

The other time I stood up to her and made her shock was when me and my new true friend went on a school trip and we got put in groups teacher picked but kalisha said I didn't want to be in that group (I have really bad anxiety on being on my own with people I don't know) and I apwent in the group and brurst out crying I managed to hold it in till I went toilet but I could see it in my eyes on that day I ended up calling her to her face a b*ch and an A-hole. First time I swore in public I don't like doing it Infront of people but I did.

Btw yesterday she pushed me into the wall calling me every name possible. She runs of with my stuff everyday. She's mean I'm fragile I take things to heart but I'm so worried about the text she sent me. Btw I'm 13 this has been going on since I joined high school. It never bothered me till now.

She also takes the Mick out of me for not being as wealthy as her and that my parents are slit up and stuff it's horrible all I want to do I cry but I don't I can't..

Any advice on what to do I really can do with some now. iv told my mum.iv been bullied before

The police thing happened today.

EASY VERSION!

Basically there's this girl who Bully's me and today I stood up to her and now she is reporting me to the police shouldn't believe it or not?