i think that what you can do is tell her stuff like " whenever you feel like the world's crashing down, talk to me. " people usually rely on things like substance use when they don't know what to handle whats around them, and that's proven by a lot of people... they don't have anyone who can immediately help them, and thus they turn to that.
i don't know what her family has put her through, but i have faith that you'll be able to help her. Tell her that you won't judge her. A lot of people keep their problems to themselves because they're afraid of being judged.
If you need any more advice or just a friend, i'll always be around.
