I have this friend who is 12 and she is like my little sister. Anytime someone asks if we are related we say yes. We are sisters. But she is scaring me

Last night she was super depressed and panicked. She is stressing over this boy that I haven't met (or approved of) yet. So it's hard to help when I don't know the guy. All I know Is that he is 13, smokes, and gets into fist fights with kids at her school. So I don't really want her near him. I am very protective of her. I don't want her to get hurt like I was.

Anyway... She was so upset she was about to kill herself and I was freaking out. I was so worried and stressed and I couldn't handle it. She cuts a lot and I can't get her to stop. She needs to understand that cutting hurts other people, not just her.
She keeps saying "it's my body I can do what I want. It only hurts me not you" but she doesn't understand. It's effecting others

I was already stressed out and now she has me worried constantly about JER safety. When I am barely safe with myself. I need time to heal and help myself and she needs me too. I can't do this.

The urge to SI is too strong. I just caved in today. And it felt so good. But bad too because I know I have problems too.

PLEASE HELP US!!