Oh Wing, I'm so sorry to hear about your daughter! That has to be horrible. I remember vividly the morning I got a call from my aunt that my uncle had called the police in mom BPD mom's city (she lived several states away from me and her brothers and sisters at that time) because she emailed a suicide note to us and he looked at his email first. I remember how it seemed like eons while I waited to hear from the police and paramedics if she was alive, and all the awful thoughts going through my head while waiting (this sounds horrible but I didn't know if I was wishing for her to be alive or not because it had/has been such a rollercoaster with her). I remember all the phone calls with the ER and the ICU, only to find out she was basically perfectly okay, just sleeping off a hangover that was made worse by Ativan. Then the hospital getting her into a rehab program and her checking out of that program in less than 12 hours...I can't get those seared images, sounds, thoughts, etc out of my mind, I can only imagine how much worse it would be if I had found her actually deceased.
My mom has BPD so I understand the suicide attempts and how they affect you too...making you always on alert, always anxious, always worried about your BPD loved one. My counselor has helped me with that by assuring me that from what she know of my mom from me that my mom will never successfully commit suicide unless it's actually by accident meaning that her suicide attempts aren't earnst attempts at ending life, but rather attempts at gaining the attention or other behavior from someone else she's looking for. I hope you've found a way to diminish your anxiety and hyper-alertness too.