My Mother drives me towards suicide

So, for all intensive purposes my name is Kat, and I’m almost 17 years old. I am a junior in high school, i am involved in Theatre, Choir, Winterguard, and occasionally Martial arts. I have friends who love me, but their love just isn’t enough. I dread going home everyday because I know that my mother will soon be there and I have to obey her every command. If i even show the slightest rebellion, it turns into a shouting match of her telling me how worthless I am and that a child’s place in this world is to be seen and not heard. We have even gotten into a couple of fist fights because she just can’t talk to me, she only yells. Everyday that my friends tell me that I can be somebody and that they can tell i have so much potential, my will to live on is crushed by my own mother. She is such a ball buster that i seriously can’t tell you what skills i have because she has convinced me that i have none. I also have a skin condition called Sebhorreic Dermatitis (basically your sebaceous glands over-produce new skin before your old skin can fall off)  that she loves to make fun of and say things like “ewww, your skin looks hideous, how can you even walk out of the house with a face like that?? You didn’t get that face from me” It wasn’t always like this though, when i was younger we had so much fun together, we would have mother-daughter days where she’d take me to McDonald eat lunch with me and buy me a small toy or little kid nail polish and do my nails. Then once i hit middle school everything changed. I didn’t want to wear dresses anymore like she wanted me to, i didn’t like bright colors, and i started to develop my own identity. Then she gave me the cold shoulder, she hated me from then on. I would come back from long rehearsals that lasted 7-8 hours in the sun or under bright lighs and instead of doing something charitable for me (like i always have to do for her) she tells me to go fuck myself. but if she comes home from her desk job i have to make dinner and if its not right then i get called a stupid whore who’s only good for sucking dick and she bets that i can’t do even that right. It’s like i am a slave and nothing else i do matters to her. I try so hard to impress her with all of my extra-curricular activities but to no avail, the spotlight is on my little brother and sister because she has totally indoctrinated them into giving up dirt on me so that i can get in trouble, and if they get anything on me thy get rewarded. I’ve tried asking my grandma and grandpa for help and to talk to her, but the just don’t want to be bothered because they are old, and they just tell me to live through it because i’ll go to college soon enough. But i don’t think i can take much more of her snide comments, her emotional and physical violence towards me, I just don’t have that type of fight in me anymore, I cut myself and anytime i have scars i pick at them because the pain reminds me that i still can feel something other than uselessness. I have contemplated suicide many times, and i think my relationship with my boyfriend is beginning to suffer because how totally broken i am now. He can see in my eyes that i am just so drained all the time from holding back my words when my mom and i get into an arguement, and he cries for me because he hates to see me so dead inside, but i just cant help it. She’s the one person i thought would be proud of me in this world, and yet she barely says anything good to me. I know some have it much worse but  i’m just at a loss for what to do, i don’t think i can wait  any longer for things to get better, and i’m at my breaking point… please help