I'm going to expose my best friend to her parents
What makes you want to expose your best friend?
I thin she needs help, she can't take care of her self.
It is bad to tell peoples secrets, they might not trust you again. If someone cannot care for themselves it is good to get them the help they need.
I'm just helping her.
If you want to help your best friend, you should talk to her about your concerns. Find out if she even wants you to get involved that way you don't humilate her. It's possible that she wants to find her own way.