Maybe distract her with an art? Does she like to paint or draw? Or do another form of art that requires you to use your body? Like maybe even dancing, or swimming, or something? Also, let her know that it's ok, sometimes things suck and it's ok to need to help. I am here for you always. If you need your alone time, tell me and I will respect that, however, every hour I will check on you to make sure that you are safe. Sometimes distractions help you to be not so in your head. That and let her know that her grades don't define her, get her to understand that you love her no matter what. Sometimes teens can put pressures on themselves that aren't reasonable. However too, like also be aware of bulling. That also could be triggering her, but she might not be able to tell you thinking that it's a failure on her part, but let her know that you are on her side. That way if she is having a problem like that she will be more willing to open up. Maybe to share examples of situations where the girl might think she "deserved to be treated a certain way" and explain to her why that isn't the case. That no one deserves to be abused. I'm not sure of your situation, but want you to be aware of all the reasons that might cause a breakdown. I don't want to worry you, just to be able to have you ask the right questions.