"friend" will not stop following me?

[randomly]

Tell her to her face that your sick of her treating u awfully, and that you think that you should both find new friends, because you are too different or something like that so that she realises that she was treating u bad, and the rest so she doesn't feel like u r ditching her, otherwise she will probably get aggressive. MAKE IT CLEAR YOU AREN'T ATTACKING HER. If you don't it won't go down well. then as someone else said, block her number, or if ur phone won't let u do that, just ignore all her texts because if u reply, in a weird way u r sort of encouraging her. If it's getting on your nerves, just be very vague with her when she talks to u. Not rude, but just a little distant. Then she might feel as if she's not so close, and drift away. Hope this helps. I know how annoying it can get!
Btw, if you can't tell her to her face, the next best thing would be a phone call. Face would be better, but if u can't wait to see her and u need to get it off your chest, phone, not text.