What do i do when my best friend hates me?

ok so i have a really good relationship with my best friend sydney we never fight and if we do its for only like 4 minutes! both of are dads died so we can express how we feel.but,i have another friend named devin...ok so we all ways get in fights she is always mad at me for something! she calls me names kicks punches and hurts me all the time and she thinks its funny so when i tell her to stop she hates me! o.k so sydney gives me a ride home every day after school,and my Friend devin who is also her friend says you should hide from her after school so she will have to walk home and devin said if you don't i wont be your friend and you cant be Sara's (me) Friend ether.so i had this video of sydney using the bath room and devin begged me to show this one 6th grader. after like 30minutes of begging i finally said ok so i gave the sixth grader a 3 second look but the video did not show any parts you were not soposed to see. so the next day at school sydney is all mad at me and i figure out devin told her that i showed the sixths graders tvideoeoo but.. devin changed it around and said.. sara showed a big group of people the video of yusinging the restroom and i (devin) was like no saSydney'seys not going to like that stop! and she just twisted it around just like that so now my beFriendisensence 3rd grade (sydney) hates me and is not going to for give me and devin told every one that story and every one all mFriendsds hate me so i sit alone at lunch and hang out by my self and the only one thadoesss not hate me is hannah and she is sick!! also devin keeps sending mthreatsts and saying leave sydney alone she is mine now! p.s devin also told her i made fun of her dad but didn'tnt i would never do that my dad is dead too! and devin will not stop texting me calling me and haring me and my mom has told her to stop like 100 times now! please help schoolto marrowrrow what do i do?