I wrote on another post...
I had 4 teens... one lovely (he's autistic and delayed and still sweet at 18), two moderately teen-like girls... grumpy, got spectacularly pissed and put themselves in danger ages 14-16, and one VILE lad...
He stole (hundreds from me) lied, smashed holes in the walls, was arrested at 16 (for something he hadn't done luckily) was curfewed informally by the local police....sold weed to friends...
Now 22, kind, loving, pays me rent, works with adults who have learning disabilities (last 3 years) doing his NVQ level 3 while there... he loves them and they love him. He plays his guitar and sings in local clubs and has saved enough to go travelling to Australia in february.He takes leave every summer to be the pied piper at a special needs kids camp where he is adored by the kids who come to dig him out of his tent at 7am 
I will miss him every second he is away. He is lovely now. Still untidy but he doesn't steal, lie, smash things, hate me or do anything untoward. He has grown up!
If, when he was aged 12-17 you had told me he would grow into a perfectly decent man, someone I would trust with my bank card, someone funny, loving and kind I would have laughed... then sobbed.
But he did. And I'm probably prouder of him in a weird way than his sisters who are in fab careers now, or his brother who fights for his independence in a world that doesn't like disabled people very much. He is a good man.
He is also grateful and very apologetic for the shit he put us through!
Hang in there!