So she knowingly goes over to this guy's house and you allow it? I would suggest you pack her things up when she's gone and tell her to move in with him.
I think it's worse to let your children know that their mom is seeing another guy and their father allows it. I understand that you don't want to make waves, but there comes a time when you have to start protecting your children from such lousy behavior.
M-43 W-40 2D - 9 and 5
Emotion, yet peace. Ignorance, yet knowledge. Passion, yet serenity. Chaos, yet harmony. Death, yet a new life.