My friend is being stupid i'm scared?

It spite of its length, your friend is obviously in a lot of trouble. It would not be wise of you to take it upon yourself to "fix" her. Until she realizes that she is the main cause of her problems with alcohol, drugs, etc., there is nothing you can do. By allowing her to stay with you, you are enabling her behavior. The relationship will become one of codependency, and eventually you will resent her for it but be unable to figure out how to end it. Suggest that your friend see a therapist. If she is still generally living at home, talk with her father and tell him your concerns. Unless he is totally oblivious to her, he should realize she needs help. Your friendship with this girl is placing a burden on your shoulders that is not yours to bear. She will never be happy until she makes a determined effort on her own to fix her life.