Should I have taken her back help?

[Margaret]

I know it's lengthy but please hear me out! Well, i have had this best friend for the past year and a half. At first she was an awesome friend we would hang out every weekend. Then last spring her other best friend (who was always second to me), was always trying to tell her not to be my friend. Like she wanted me out so she could be my friends only best friend. I started dating my best friends brother and anytime drama would happen my best friend would go tell this other friend, which I am uncomfortable with because she doesn't know me on a personal level, and I have asked my best friend to keep this other friend out of our business but she never does (after saying she will). Well in October I noticed my best friend posting all this stuff on Instagram saying the other girl is her "#1 best friend and favorite person ever" and then deleted all our pictures as if we were never friends. So i got mad and called her out on having been a bad friend lately and after that we didn't talk for 3 weeks. During that 3 weeks, she so quickly moved on to making this other friend her best friend. She deleted our photo album titled "best friend" and made one of her and that friend titled "best friend". And she changed my name in her phone from "best friend" to my name and made the other friends contact say "best friend". Then, one day, SHE texted ME saying she wasn't the same without me in her life and wanted to be friends again. I asked her why she deleted our pictures and she said it was a misunderstanding and that she was just trying to "clear up her Instagram" and "didnt mean to make it look like she was only deleting our stuff". So we have hung out since then but it has felt awkward for me because I feel like I can't trust her and I feel like I'm only keeping her my friend because my other best friends are moving away for college so if I don't make new friends (which I doubt I will as a senior) then she's like all I have until I move to another state to room with another friend in a year and a half. I don't know if I would be happier without this "best friend" even if it meant being alone. 3 weeks ago she asked me to room with her then last week puts on twitter "so ready to move with my best friend!" And tags the other friend! Then when I asked her about it she played dumb and shifted the blame on me which she does anytime I call her out. Thats why I feel like I can't talk to her about how she's acting. So what do I do?