First lets define Borderline Personality Disorder which is thought to be learned behavior which unlike other mental illnesses are more genetic in nature, The hallmark of BPD is the instability of interpersonal relations,;extreme swings in emotion and mood from extremely good to extremely bad with anger, depression and anxiety; there is an increased chance of self harm or risk taking behavior (it is quite possible that the physical injuries you described were self inflicted).; attention seeking; and possible transient psychotic episodes. I have enclosed a link with more details: http://www.nimh.nih.gov/health/publications/borderline-personality-disorder-fact-sheet/index.shtm
The first thing that you can do to help yourself is to stop blaming yourself and give up the concommittant guilt that goes with it. You have no control over her behavior. You can feel conditional love while at the same time abhorring her totally inappropriate behavior. If you continue feel unjustly responsible, depressed and guilty, you may wish to seek individual therapy for yourself. I would suggest that it be a therapist who uses cognitive behavioral techniques. In CBT you learn new ways of thinking and acting and as a result there is an improvement of mood. Here is some information on CBT:
As far as your daughter is concerned, in the past the outlook was candidly somewhat bleak. However over the past few years a new an effective means of treatment was developed which has proved fairly successful called Dialectal Behavioral Therapy.
See http://en.wikipedia.org/wiki/Dialectical_behavioral_therapy .
You need to not empower her or reinforce her behavior by giving it credence and reacting to it. If she is able to make you react emotionally rather than rationally then her illness is reinforced. I hope that this information has been helpful, but again there is reason to believe that with the correct help both of you will do better!
If you require further clarification or more information, feel free to ask!
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I anticipated this question and previosly answered it. If it does not come through let me know and I will repost.