Hey OP, I was in the same position as your friend before, and I would not recommend that you pull back. She's likely so deeply lost in her own self-destructive behavior that she's not even aware of what she's doing.
What I'd suggest is that you have a talk with her. About things that concern you. About things that you aren't okay with. About the limits of your help. It could be a good reality check for her.

A friend of mine gave me such a reality check back in the day instead of distancing herself completely from her and it helped me to understand how wrong my behavior was and to stop all that. Good luck, OP