Okay. Just to say: my english sucks ( english schools in brazil are a joke :v ), so, ill try to help with what i understood.
First of all, i already felt like that. I tryed suicide, and listen carefouly: its not worthy, it hurts and now i have some shit in my arm; and life is beautiful, be patient my boy, bad moments come, bad moments go, and things that doesnt kill you makes you stronger. So, beside you feel "useless and defeated" welp, try finding some hobby, and study, beive me, good grades makes you feel useful. Defeated? The game of life only ends when the game is over. Its a matter of time my boy. Try drawing what you feel, listen to music, you know? The happy is im minor things
I hope i helped you! And if you did read it to here, congrats! ( because i wouldnt have patience xD )