Why does my friend do this?

I have been cutting for five years. I recently got home from being in treatment for two years. I cut myself because i wanted control. It became an addiction when i tried to stop... but could not.. My only advice is to tell your friend that you will be there for her... and tell someone who can do something about it immediately... many of my friends knew i was a cutter... but did not say something about it... so it got worse. Help your friend out now... before it gets out of control.