I have sole custody of my 8 year daughter. My exhusband gets supervised visitation every other Sunday for six hours . I juswe go to court in June because he wants more. I found out he now lives with a woman who lost custody of her own children (I don't know why) and becomes very violent when she drinks. Which is quite often. She has broken gifts things from an iPhone to china last week the police were called because she threw knives at him. Obviously I don't want my child anywhere near them. I'm not sure what to do. Can I find out why she lost custody? Oh and in 2009 she was arrested for theft with a $5000 bond. I'm sickened and scared.

You petition the court to require him to provide this information.
Your attorney should know how to do all of this

But if it is supervised, then there should not be a issue, is this at a court provided supervision center ?

If the visits are supervised outside the home, you can require that she not be present.