Fraggles, my former step-daughter was a "cutter." At one point, she had a bit of a breakdown and was institutionalized, where she was diagnosed with Borderline Personality Disorder (BPD). Self-mutilation is one of the symptoms of this condition.

BPD is a very difficult condition to treat, as many of those afflicted neither want help, nor do they acknowledge having a problem.

WebMD has an article on self-injury here. According to the site, cutting may be a manifestation of one of the following:
  • Personality disorders (particularly borderline personality disorder)
  • Bipolar disorder
  • Major depression
  • Anxiety disorders (particularly obsessive-compulsive disorder)
  • Schizophrenia
The bottom line is that you're going to have to get mental health professional help.

Good luck!

Preach the Gospel every day. When necessary, use words.
St. Francis of Assissi