The best thing you can do is to be a friend. If she feels the need to self harm, nothing you say is going to change it. Telling someone in authority will probably just make her pull away from you, and chances are they won't be able to do much about it until she really hurts herself badly enough to need a hospital.

People tend to talk more about private, embarrassing or secretive things at night. Especially on walks or long drives. Probably because you can't see their faces and it gives them some sense of privacy while being able to talk at the same time. See if you can get her to do either. Let her bring up the problem and listen. I doubt she wants answers, but in all liklihood, she wants to make sure that you won't leave her or think she is weird.

You have nothing to feel guilty about. The weight of that kind of knowledge is almost unbearable to carry by yourself, and here, you are faceless and nameless.

In my early twenties, I had an on again off again friend. We had been tight when we were really young, but lost touch when she developed bipolar and shut me out. One night, I was walking home and passed the elementary school she was working at. She was a night janitor. She let me in the door and we talked a little. Then she went to the closet and handed me a boxed electric knife. I knew she must have been considering killing herself. She never said don't tell, or asked for help. Handing me the box really didn't need much explaination. I never told anyone, but it bothered me constantly. I didn't know whether i should tell someone and break a trust or keep my mouth shut and let her work it out. Had she gone on to kill herself, I don't know what I would have done. Things turned out ok, but it was like a load of bricks on my shoulders holding in that knowledge and not knowing what to do with it.

Go with what your heart says. Most of all be there.

Sam2