It appears that you are doing a lot to protect your son. If you believe your son is in imminent danger and that visitations should be stopped or supervised, then you can file a Motion for Temporary Orders or even a 209A restraining order. You should also hire an attorney to represent you. If you can’t afford one, try calling Community Legal Aid - Worcester, (508) 752-3718 or the Lawyer Referral Service from the MA Bar Association, 800-392-6164. Good luck!
Gary S. Sinclair is an attorney licensed to practice in Massachusetts. If you wish to contact me or any other attorney on AVVO, just click on the attorney's name and you will find contact information. All of my answers are based on Massachusetts law or a simple reading of the law in your jurisdiction. All answers are for educational purposes and no attorney-client relationship is formed by providing an answer to your question. The information provided should NOT be relied upon for making legal decisions. You will be best served by hiring an attorney in your area who specializes in the field of law pertinent to your question.
If your son's well being is at stake I would be a bit more aggressive and file for temporary orders to stop visitation until an investigation can take place. Have you documented the bruises, and how do you know the living conditions are unacceptable? An experienced attorney can help you negotiate the court system in a way that will help protect your son.
This is not legal advice until I am retained and have reviewed all facts about your situation.