The curriculum gets to the root of the problem. The content of the program is set up to challenge his underlying belief system that he has the right to control and dominate you. Programs that only address his anger, communication skills, and stress do not get to the root of his problem. Makes no demands on you to participate. You're not the one with the problem.
Some programs offer groups for partners of batterers.
Your participation must be entirely optional. Don't let anyone lead you to believe that his progress is dependent upon your participation. Is open to your input. If you initiate contact with the program to ask questions or give input you think may be useful, a program should welcome your participation. This is different from requiring you to participate.