How do I cope with someone bullying me?

Hello, I will start by introducing myself. I am a female and currently in high school. I have had very little friends my whole entire life, mainly due to anxiety and lack of self confidence. I am very shy, and find it hard to talk. Last year, I made two friends who I mainly sat next to in class all the time. I knew one of the girls back from my childhood, and we didn't really have a good relationship back then. She always talked behind my back, trying to get my other friend to stop being around me because she didn't like me. We eventually warmed up to each other, and she would be kind to me ocasionally. Most of the time she would insult me, but I knew that she didn't mean those things. Some of those insults included her pleading for me to kill myself, (which, eventually I tried) and her mocking my weight, appearance and a whole lot of other things. She would mention stupid things I would do when I was younger, using them against me. I became sick of this fast, but I always put up with it because I didn't have any other friends. This year, I carefully planned out my timetable to talk to them less and less. I realised I would rather be a loner than to become even more depressed. I have done a good job of doing that, but my old friend (the one who didn't bully me) wanted to play sports with me. I agreed, thinking I probably couldn't get a team without her. Since then, my old friend (her bestfriend) has been constantly harassing me wherever I go. Whenever I'm walking to another class she'll whisper something demeaning into my ear. I signed up to music lessons, and I unknowingly got put into her sister's class. Today she came up to me, in an extra loud voice and told me that I suck at learning music. I know that this is absolute bullshit, because we've only had one lesson so far. I'm so sick of her. I don't know what to do, I feel trapped and iscolated. I've messaged my old friend (the good one) asking her if we can talk. I don't feel like messaging her will do any good, but I hope it will. I don't have much of a conclusion, but I would really love it if atleast one person would respond to this. I am in desperate need of someone to talk to.

edit: okay.. so yesterday night I talked to my "good friend" and she basically told me she doesn't care. also, the "bad friend" made fun of me again today. i feel done with life in general. goodbye.