How Can I Stop This Friendship Problem?

On the first day of the school year this year I was usually thinking about things and walking around during recess. This other girl, which everyone says is weird thought I was lonely and started talking to me. Every day that first week, she spilled milk all over me on accident. For some reason she became my friend. I think after a small little tiny conversation, she thought I was her BFF. So after that, she started sending me lots and lots of pics with so many hearts, a picture of me, and a picture of her holding hands! Also even more that kind of creeped me out a bit. She started giving me no space(trying to get me as her partner, following me wherever I went and I mean everywhere, not letting me have space, sitting by me everyday or budging people just to be next to me online, and much much more. Then on Halloween, I made a friend. She made me less shy, made me feel better about myself, made me happier, and helped me a whole lot! I also helped her too. The other person got upset and started bullying and threatening me(kicking me, saying that she'll find my other friend and say i'm not their friend anymore, rip my things when i'm not there, taking my homework, and more) She starts crying and saying I'm the worst person ever. I try to tell her i'm trying to talk to my BFF about her crush secretly but she just wont go. After that they started competing about who is my BFF. My BFF is trying to help me and figuring a way to tell her that it is bothering me the way she acts in a friendly way and we don't want to tell because she will cry and I will feel very bad.(I'm one of those very thoughtul people that can't stop feeling sad about anything) and if I tell her she gets upset. I can't do much and she is starting to get the problem worser and worser. It puts lot of pressure on me because she glares at me too. It's very hard on me because I can't do anything! Can someone help me with this problem? I don't want to go to school knowing this is going to happen again and this girl is a person who never gets in trouble, innocent(well in cl),smart, and gets offended easily. I don't mean to say she's the worsest person and that I hate her plus I don't like saying anythinga bout people so i'm kind of taking a risk here lol. So can someone help? Oh yeah and we're all GIRLS! ^ ^ Sorry. I felt like I should say that right now