BPD daughter

My daughter is in a domestic violence relationship and has tried to leave twice in the past month but keeps going back. She has 2 young sons who are being affected by this situation. 2 days ago she asked me if the boys could live with me temporarily so they are safe. Of course I was relieved and agreed. She was to pick up the kids from their father's at 5 and bring them over. She didn't pick them up and when the boy's father finally got hold of her, the boyfriend answered her phone. After a couple of minutes she told the boy's father that they would be better off with him and relinquished custody of them. She's blocked my number and I don't know what to do. My psychologist says I need to let her stand on her own 2 feet. She always relies on me for help with babysitting and money yet she has been telling me she hates me. She blames me for everything wrong in her life. Her boyfriend validates all her reasoning and tells her that mental health disorders are bullshit. He says she can make herself happy and has tried to get her to stop her medication. She has had 2 suicide attempts in the past 3 years and I'm afraid she will try again when she realises she has given up her children. Does anyone have any advice. I'm losing not only my daughter but also 2 grandsons.