as someone whos been on your daughters end of this situation, here is my perspective. keep in mind that i dont know you nor do i know your daughter, so all of this is mere speculation and i could be 100% wrong. although this rarely happens, its still possible;) so heres my take, direct and to the point.
first of all, from what ive read i dont believe your daughter is trying to kill herself. its hard to do just by cutting yourself. i mean it would have to be perfect; the right angle, the right depth, etc. if youve seen her scars, try to remember what they looked like - were they horizontal or vertical? practically the only way to successfully so much as graze the crucial vein would be a vertical incision, which many dont do because either theyre not really trying to kill themselves, they arent familiar with the technique, or most often its because its somewhat of an unnatural position. horizontally is the way that is most comfortable and allows you to use the most pressure. anyways, this is just what ive found from my experiences as a cutter and just from research. besides these reasons, if someone truly wanted to end their lives, they would use a different attempt that is proven to be a more "guaranteed" method.
when you first approached your daughter, she was honest with you about cutting herself and revealed why she did it. then a second time she actually sought you and confessed she was contemplating it. these are two SURE signs that shes asking for your help, begging for it even. the worst possible thing you could do is ignore it or treat it as though it were insignificant. most who cut, aside from many other psychological reasons, are basically asking for help, especially if theyre not careful enough to hide their tracks (both literal and figuratively). you found a bloody towel in her room, and with not too little effort it seems. someone who didnt want your help or who were further into their illness and wanted someone to prove they are willing to sacrifice in order to help would have disposed of that cloth immediately and made it incredibly difficult to discover. as dark an example as it is, think of how some serial killers are notorious for leaving behind some sort of clue at the scene of the crime. 9 times out of 10 these clues ended up assisting the investigation and eventual capture of the criminal. why would they leave such clues if they truly did not want to even be caught? they use their clues to establish some sort of relationship or connection with their pursuers. its like saying "im going to do what i want and continue with my self destructive behavior unless you prove to me that im worth fighting for." im sure i dont have to elaborate even further to demonstrate my point.
it wasnt until much later in my life that i realized my real purposes of cutting. i realized i was begging for attention, something every child desires from their parents no matter what their outward behavior suggests. at the time if my parents were to try and accuse me of that or even suggest that it could have been a motive to my actions i would have only been pushed farther away. so whatever you do, do not try to reason with your daughter as to what could be causing her to do this to herself.
my advice as a past cutter who knows what its like to be left stranded, is to first and foremost make time for her, no matter what the cost. if it means having to take off work a couple nights, or tolerate a disgruntled husband/ex husband, or spend money that you dont have on a movie or dinner date, do it anyways. nothing is more important right now than the health of your daughter. instead of beginning a conversation with the topic, try suggesting a movie that youve been dying to see. most likely if you catch her off guard and directly ask why shes cutting herself, shes not going to be as willing to divulge such information. i think the best idea would be going to get some coffee together. its quiet, offers privacy, and you wont be too busy chewing to talk. talk to her like you normally would, and somehow graze the topic of schoolwork, plans for her future, etc - whatevers relevant enough but not too specific so as to leave your true intentions so blatantly exposed. in my opinion, i think that relating things in her life to yours or to what you had experienced at her age is a good way of leveling the plane between you two, so that its not so much of a mother daughter conversation as it is a friend to friend conversation. shell probably be more responsive than you think. and dont downplay her situation by inferring that its "just a phase" or "you went through the same thing and got over it". though these statements may be true, she hasn't the same perspective. shes still struggling; its only after the battle that we gain objective insight to the situation, if at all. instead, ask her why she thinks shes doing this. dont seem like you already know the answers, because you may very well not. never in any way come off as pretentious, condescending, authoritative, or threatening.
the most important thing you can do for her is be a safe haven. she may not always come to you if she needs help, but if you establish a certain trust and consistency in your actions, shell always know in the back of her mind that should she need to, youll be someone she can always depend on when all else fails. when you guys finally begin to discuss her problems and whatnot, after asking for motive, ask her opinion on the subject of help. is this something she can handle alone? does she think a counselor could help? how long has she been feeling so desparate? if she says she can handle it on her own, take her word for it. but openly maintain that if she hasnt proven to you that its under control, you will get in touch with a therapist (that is if shes under 18 and you have the legal right as the parent).
im so sorry for what youre going through. i know how hard it is to witness such anguish from a familymember for whom you take protective responsibility and to feel inately powerless in ceasing their pain. however, i do not have a child, and i am sure your inability to protect her is a completely different sense of helplessness. but know this: ultimately you may have no control over what she does to herself, but you are in a key position to substantially influence the outcome of her behavior. you have the potential to play a very key role during this ordeal. all you have to do is be available - and of course, very willing.
if you have any concerns or questions or just want to talk more, feel free to pm me. good luck with everything. hope i could help:)