well the only thing you can do is sit her down and talk to her. Tell her logically the reasons you don't like him as husband material for her. Don't bash his personality, but focus on the things like the illegal things, and her having to support him. Tell her that if he hasn't changed in five years, marriage isn't going to change him either. Also, tell her that since he is involved in illegal things, you won't be having him over to your house and/or around the kids in the family, because you need to protect the kids. What else can you do? If she's determined to screw up her life, there isn't much you can do, except point it out to her and pray that she comes to her senses. Also, I suppose you could call the police and report his illegal activities, but you need to know that she may never forgive you for that, and you have to be willing to live with those consequences.