Oh, that poor baby! I don't know how anyone can abuse a little (or any) dog like that. Since the shelter is so close, is it possible for you to go and visit him everyday for a little while? Maybe if he's at the shelter and you visit him and take him a toy or treat and just sit with him and talk to him and hold him, he will begin to trust you. It might help because he'll see that you keep coming back and that you're good to him. I sure would at least give it a try. And, it would help you be able to see him which might make you feel a little better. I think he's just scared and he's acting out (out of fear) because he doesn't know who he can trust. I worry that he won't be able to be rehomed because of his behavior issues, and it's so not fair to him because it's not his fault that he was abused. Poor baby! The people who abused him should be shot!
Good luck to you!