How can I help my friend?

I don't know her in real life, we just roleplay together. Today she said that the hospital might keep her on suicide watch if her 'plan' goes through. I'm really scared for her. She said that she cut a Roman numeral 2 on one leg, an X on the other, and an X on one arm. She won't cut herself deep enough to bleed, but she still inflicts pain upon herself. Her parents don't know that she is doing this. How can I help her? I know I've never met her, but I really care. Help, please?!