If all of this fails, remember to make sure you are safe and take care of your injuries. Try to keep cuts shallow. Keep first aid supplies on hand and know what to do in the case of emergencies. Do only the minimum required to ease your distress. If you can manage that much, then at least you will be exerting some control over your self injuring.
Self injury can be hard for family and friends to accept and understand.
For detailed information on helping and dealing with someone who self injures, go here. Remember, there is no shame in mental illness. There is no shame in doing what is necessary to survive. But there is shame in lack of understanding and acceptance by society. More education is needed about mental illness to help people understand and accept it.