My Daughter is choosing her boyfriend over her family?

There is really nothing you can do about it seeing she is an adult. She has to figure things out for herself. You have already tried to have a family discussion which failed. You could try having another with just her and your granddaughter voicing your care and concern. If you chooses to leave though you can't stop her. Maybe someday when things get to be really bad she will realize that you were right. Most people have to learn things on their own.