Child support and garnishings?

My husband has an ex wife that he shares a child with. Both live in separte states ( mariland-kids living most of the time, and the father is in california) . He pays child support each month and had the kid all summer long ( 2.5 months). I have 2 other children by someone else and we have alot of bills, some months of child support are late (however they always get to her). She is threating to garnish my husbands wages for child support and filled ( she says but we have not heard anything yet. also demands child support now my husband also pays ALL medical/dental/vision).. She states that it does not matter his bills or our family and that he has to pay no matter wht the reason. However, his money is half (retired millitary) wht it used to be when they divorced and thats not being consided at all by her. Wht can we do to stop the garnishing and threats? We do wont to pay child support but we dont want to go homeless doing it.