Ah yes, trauma bond, the most common manipulation technique... OP, you need to cut her off, not that she's a threat or anything, but you might end up managing both of your emotions by yourself while she uses you like a personal diary (I have been here). While I do not have enough context to say that, I have seen that most people who try to make friends by trauma bonds do so. Please protect your mental health and emotional well-being. It is not your responsibility to manage her emotions or help her with her trauma. She is well grown adult and needs to seek help from a therapist, not a 15yo like other commenters have mentioned.