No advice but here to lend a sympathetic ear. That would be tough news to hear, especially given your concerns about your daughter. Does the boyfriend seem more emotionally stable? How long have they dated? If it’s been a while, he may be aware of her issues and well-suited to support her personality and emotions.
It’s so impossible to know from the outside what any relationship is like on the inside. I hope you have more discussions and that they are productive.