I am really sorry to hear about this. I have struggled a lot with friends being toxic. For me, one thing that I have found to be helpful is to just listen. People sometimes want to be reassured, but first, let her talk. Once she gets what she needs to say out, she may be willing to apply and to also listen to what it is that you have to say. If she is seriously considering ending her life in the near future, it is best to physically go and be with her in order to keep her preoccupied. If being with her physically is not possible, keep her on the phone. Remember that a good friend will tell a secret to save a life even if it may ruin a friendship. Also, make sure that in re-involving yourself in her life, you are not causing damage to your own. If it gets to stressful or scary, ALWAYS seek help from someone who is trained in your area. You can show her that you care, but in order for you to help her, you also need to be in the right state of mind. If involving yourself too deeply causes you to be stressed, you are not in the right state of mind, and you will really only be hurting yourself. Make sure that you take care of yourself as well. I am going to keep both you and your friend in my prayers.
I hope that this helped.
