I'm sorry to hear this. I know how much you have to deal with. People with BPD tend to be extremely sensitive. Small things can trigger intense reactions. That's why your daughter "throw things and said horrible things" to you. When she is in the throes of overwhelming emotions, she is unable to think straight or stay grounded. She may say hurtful things or act out in dangerous or inappropriate ways.
But stay positive and have faith. BPD is treatable. Its long-term prognosis is better than those for depression and bipolar disorder.
Does your daughter have a therapist? If not, getting one is a good start.
Now, as a mother. You can take steps to improve communication, ser healthy boundaries, and stabilize your relationship with your daughter.
1. Listen actively and be sympathetic. Set aside your personal judgement, withhold blame and criticism, and show your interest in what your daughter says. You do not need to agree with her, all you need to do is listening and by sympathetic.
2. Calmly reassure your daughter and set limits. Say things like, “I love you and I want you to feel better, but I can’t make that happen because of your behaviour. I need you to make some change for yourself and I will always be on your side.”
3. While you should be patient and loving, don't tolerate abusive behavior or enable your daughter by protecting her from the consequences of her actions.
My suggestions might not be enough. But I hope these tips can help a little. Best wishes.