Best Friend?

Okay so there's this girl I'm best friends with or at least I used to be best friends with. It all started back in first grade when we first became best friends leading all throughout grade school into Middle School seventh grade is when everything went down. She dated my ex that I dated for 8 months. I figured maybe I'd be okay but eventually I wasn't. They dated still are for a year-and-a-half now and every here and there he would break up with her and text me. And of course I would text him back because I'm still madly in love with him I know I know grade school middle school love but I've been close to this kid ever since I was born our parents grew up together which caused us to grow up together. But anyways whenever I would talk to him she would flip out spread rumors hate on me and she doesn't even realize that I let her date my ex so she was happy. But when I want to make myself happy she wants to ruin my life.. I swear this girl is weird. We just got into a huge argument about a week ago and she text me acting like we're best friends. And to be honest I don't really want this girl in my life she's bad always gets into drama and I don't need that. I block her on everything and she still somehow gets ahold of me. I don't know what to do on whether or not I should still talk to her and not have my life ruined. Or stop talking to her and her spread rumors about me all throughout the school all throughout town to just everybody and her completely ruined my life... I need advice on what to do because if i drop her right now when school starts she said she's spreading a lot of rumors around about me. I only know this because sje told a couple friends that told me and I'm really nervous because I'm just entering high school and I don't want my reputation to be ruined during freshman year my first year of high school..