<< All of them have improved their grades which is huge as it was a big concern. They look happier and we have set in to a very nice routine at home.
Yup! I had my kids for 3 months continuously and it was exactly like this, more peace, routine, and top grades. In these awful 'sitches' we often have to grapple with the legal vs. moral - the former often trumps the latter. But in your case you have the ball almost entirely in your court with respect to the kids which is a good thing given your W's sick head. Hope you find a cleaner neighborhood soon! Try to build rapport with parents of your kids' friends; assuming they come from good families this will raise your self-esteem and give your kids hope for a better life.