well it could be just a growing phase. You have to make mistakes to learn right?
i've had friends that were on drugs and went nuts for a few years in their early 20's and got all that craziness out of their system and now are well adjusted clear thinkers and happy people, they have regrets of course...but thats life. I made a choice to stay away from these people until they became normal again, which took about 6 years....so if this girl is dragging you down just don't associate with her.
Work like you don't need the money. Love like you've never been hurt. Dance like nobody's watching