I used to have an extremely similar problem. I was addicted to self harm and am still recovering, and my best friend got into it as well. I felt terrible and partially guilty like "if I had never have done this, she would probably be okay" which I realized later on that wasn't true. Having a best friend who also self harms is one of the hardest things ever. Because you want them to stop because you care about them and don't want them to harm themselves, but at the same time look what you're doing? It's almost impossible to encourage them to stop because you're being a sort of hypocrite. And I'm not pointing fingers at you at all, I'm just talking from experience and how I felt. Advice: The thing that helped me get my friend to calm down her cutting habits a little was reminding her any chance I could that she was amazing and just compliment her all the time. Any time she would start to text me she wanted to cut I would immediately call her and eventually lull her to sleep. I know it probably sounds stupid, but maybe you could try? I really hope everything goes alright with you and your friend. You can always talk to me more about it if you'd like, I would love to help.