Can a 17 year old decide to move from his father's house in NJ and live with his mother in CT?

The 17-year-old young man was living with his father in NJ and attending a private school for the past 2 years. I was his choice to go there in order to have a relationship with his dad - the parents have been divorced since he was 6. It turns out that the father is abusive - recovering alcoholic, (abuses the boy verbally, emotionally and mentally) he is threatening and hits the step mom and they are always fighting and the son is in constant fear of the fight spilling over. He just came forward with this info - and decided to withdraw from the private school in NJ and he moved to CT with his mother and started public school there. The father is threatening legal action - harassing the son and his mother. What can the 17-year-old do? What are his options? His rights?