I Battle Depression

Well I'm 15 years old and a week ago I attempted hanging myself but all I could think about was how people would say I'm so selfish. I luckily slipped out the noose and when to my mentor at school, I told her I just didn't care anymore. She told me to go see my GP but I still haven't gone. I really regret not doing it because I'm failing school so bad, I can't even get into college now and my grades are so bad for an apprenticeship. What am I meant to do with my self I'm getting so frustrated and angry now even over the little things and no ones helping me. I'm dying here, the temptation to grab that rope and jump. please forgive me