Toxic Friendship // soz for the huge para💕

Lydia • Follow me on insta: lydia_gillxx
So I have this friend, she obsessive.. I can't have any friends without her freaking out saying that they're taking me away from her, or that I'm choosing them over her.
At one point I saw her as the bestest friend, but when I realised I had lost all of my friends because I chose to keep her happy. 
She however, has now gotten really close with my used-to-be-close friends and every time I try to get close to any of them she freaks out on my again.
She says we're best friends and that I'm her "fave person"... but she makes me miserable. She is possibly the most argumentative, disrespectful person I know, especially to her mother. And thats something that goes completely against my values. 
What do I do? How am I meant to get away from her?