Hello gloamingone, I feel for you. I wouldn't force him to come and live with you but try and spend as much time as possible with him and talk to him about possibly talking to someone at college/school. There is usually a counselor attached. It is difficult with a teenager I know, push too much and he'll dig his heels in even more so you need to somehow make it his idea. Be the rock you have always been for him.

Edit to add: If you feel he is being abused then the right thing to do would be to get social services involved.