~First off, I don't want tp be judgmental, but she's 13.....and she was pregnant? Ouch. That's sucky fate.
~I have the same problem. But just not as extream. My friend will text me sometimes saying that she wants to commit suicide and no one wants her here and a bunch of other stuff I don't remember. I know how hard it is to be in your position. You don't know what to say, or do, and it stresses you out so much that it hurts, and for that I'm sorry.
~The thing is, when someone is set on killing themselves, in the heat of the moment, nothing or no one can talk them out of it. So I would say try to keep her as for away as possible from those situations. If I were you I would have her speak with the school councelor or something. She might get mad and be all "I Hate You" but she just has to see that you are worried for her life. I know I would do that if my friends turned me into the school for cutting, I would be extreamly mad at them, and not want to talk to them, but I would understand. Hopfully she would too.
~Explain how you feel to her. She's imporatnt to you, and you don't want to see her going through so much pain. Offer as much help as you can. When most people are dealing with stuff like this, what they normally need is a hug or a talk with someone close.
~After you have done all you could've possible done, talk her parents into sending her to a hospital. You yourself said she could quite possibly be mentally insane. And someone her age shouldn't be getting pregant, doing drugs, and wanting her life to end. Really, if nothing else has helped her, this is your last option.
~I give you and your friend my love. I am so sorry, dear, that you have to go through this. I hope everything gets better. xoxo Cara <3