Dotty, I havent read all the posts on this thread but I read the other post on general. Your daughter HIT you!
You keep saying you were or are a bad mother. I have no clue why you are saying that. Is it because you tried to convince your daughter to not go date this guy? If so, then I am also a horrible parent because I flat stopped my middle son from marrying a girl. I have also had spats with his current wife and my youngest sons oldest's baby's mother.
Trust me, I dont take well to anyone hurting my kids and I am not afraid to let my feelings be known. If anyone doesnt like it, I dont much care. They can get happy in the same hand they got mad in.
Your daughter is fully able to make her choices and if she is abusive to you or hits you, you cannot take that. She will either figure out the Bozo on her own or not. That is up to her. If you feel he is wrong for her, I dont blame you for warning her. But you cant feel you are a bad mom for doing that. You did what you felt was right now go on with it. If he is that bad, let her be. Dont bug her.