My 18 yr old daughter moved in with 29 yr old boyfriend and his mother. She quit college, and has all but quit communicating with family because we do not agree with this. He has no job, no car , two children whose mother he did not marry but did marry a girl to "prove he would do it" to the mother of his children, and has had frequent run ins with the law. My daughter now says she is going to marry him. What do I do because I know this is a huge mistake. I never had trouble with my daughter before he met this man. Help

There is nothing you can do. She already knows how you feel. Whether you think it is a mistake or not. Does not really matter. The reason being is that your daughter is 18 years old. She is an adult. That does not live with you anymore. She needs to grow on her own. Learn on her own and make her own mistakes whatever they may be. I know it must be hard but the more you try to interfere. The more your going to push your daughter into making rash decisions.

All you can do is tell her how you feel about the situation but in the end you can not force somebody not to do certain things. You can certainly let her know how you feel and why if she is willing to hear things but in the end whatever she does in life will be her decision alone.

If I was you. I would cut her off completely. And not have anything to do with her, and let her suffer.

Well honestly there is no control for her to get out of in the first place. So she isn't 'out of control' she is 18 years old and shouldn't BE in anyone's control.
You need to let her make her mistakes, live her life the way she chooses, and hope that she grows up and sees you for the loving mother you are

She is 18 you have no say really. You may want to call your local family court however to find out at what age and circumstances you are no longer legally responsible for her actions. Although you still have no say in what she does if she gets into any legal trouble you may still be liable. If you are still liable you may want to ask what needs to be done to relieve you of those possible responsibilities.