What to do about Irresponsible parents?

I'm 15 and my parents don't know crap about me. They only keep me so that one day i can make them look good. Yeah sure i respect them. I love them for giving me a life and a chance to live. But still... I've never heard them say sorry or thank you or i love you. They always want me to study and work hard towards school. But SO many things been happening in my life that it's hard to keep my mind on studies. So instead my mind was always focused on life. I understand life more than most kids my age should. It's like i gained all the expirenced too fast. And thats not good. I can't keep up with school because my parent's DO NOT have ANY faith in me what so ever. They think I'm a waste and shouldn't even be living. They do not apologize when they say wrong things. But I do. because i understand life more than them! I've been in love with someone before. I know how hard life can be. I've been through SO much pain. And my parents STILL push me harder. I can tell my dad hasn't. Maybe my mom has but she's too stubborn to help me with anything. When i try talking with them they just ignore me. When i say all these things to my dad he just says I'm stupid and my brains messed up. My dad is about to devorse my mom for another woman. And all my siblings i've never been close to because they are too young to understand life as much as me.... you might think i'm crazy so go ahead. But i'm just thinking of what i should do about this? My parent's should have been more responsible before having me...... I thank them for giving me a chance at life. But i'm also dissapointed that they can't even have atleast a little faith in me. I've been kicked out many times but taken back because they don't want to talk to cops.... No i have never thought about suicide because it's useless. I understand life alot. But geez.... This one's hard.....