Indirect Bullying

Hi everyone!! I'm going to give you guys a bit of backstory before i get to the nitty gritty of this. I'm a 15 year old girl, and I'm a sophomore in high school. I know a good amount of people have been indirectly bullied in their lives and I just need some advice. There's this girl at my school that is trying very hard to make my friends hate me. I know that sounds very childish, but it really does hurt my feelings. She threatens to do all these embarrassing things to me and she has said that she wants to ruin my life. I've tried my best to ignore her, but I'm about to explode. I've told people what this girl is doing and how she acts towards other people and they don't know how to help because there's no proof of what she's doing. I've told teachers and I've told my parents, but they won't do anything about it because there's no proof. This girl just has it out for me and I've tried to confront her about it but a huge lump in my throat shows up and I just break down and hide. She's been doing this for a year now and I just want her to stop but it feels like I can't get her to. I'd really appreciate it if i could get your guys' input on this, I feel like I'm pushed up against a brick wall I can't get around. So if anyone has gone through a similar dilemma, please let me know what you/they did to get it to stop. Thank you for reading and have a wonderful life, you're beautiful!!