Sorry, here's the link https://www.amazon.com/Bright-Red-Scream-Self-Mutilation-Language/dp/0140280537
One of the major things that stopped me cutting was yoga and exercise. Its hard to start though, especially if depressed in the first place.
I found it instilled a basic level of respect for my own body which helped reverse a deeply ingrained self-hatred.
Self harm is something that she will live with her whole life - even when she's stopped. There will always be that temptation to start again when stress gets intense.
I'd like to reiterate what Lennox said: Don't make a big public issue out of this. It'll only make her be more secretive. Be there for her, don't berate her - if you make her feel like even more of a failure or bad then it may cause it to happen more.
Wish you all the best. It won't be easy to be supportive and you may get very frustrated at times. A book that may help you understand a bit better is called Bright Red Scream.