Dating a '' bad boy '' is not as cool as it seems...

My friend and her boyfriend just broke up and now she's depressed. Okay, typical.
But we all think this breakup is the best thing that happened to her.
She used to have good grades, came everyday to school, had many friends. She was a great person and we used to have a lot of fun together.
But then the guy came in, and...We stayed friends of course, but we noticed that...She was changing, and not for the good.
He used to tell her to skip classes, to try to smoke, to try idk what drugs or herbs or whatever, to try some drinks, to go out with him in the middle of the night to some places that she's legally not supposed to go to. She started being very rude to people, and many of her friends left her, but she didn't care.
And we tried to tell her that he's ruining her, that he destroyed his life and now he's unconsciously destroying her, her future and her life.
But she would always reply by saying that she was having fun, and that her life used to be boring, and now she feels alive. That he cares about her, and only wants her to taste life and stuff, which I believe, I mean, he's a good guy deep down, just...Not for her ?
Now that they broke up, I'm dealing with a huge mess of a friend. She's broken hearted, she's depressed AND she was excluded from school and has to change high school, she lost many friends, she can't stop smoking...
I don't know what to do to be honest...