you said there were two groups one your boyfriend is in and the one you are in. how about trying to switch groups. I did that when I wan't comfortable with a depression management group. I knew I needed to go but the group I was in had 4 people - 3 guys and me and one I just wanted to strangle him because he came in every week with the same problems and never tried any of ours or the facilitaors suggestions. And then there was the fact that my abuser was a man so I wasn't comfortable being in the room with 3 men. So I switched over from that group to the evening group. which was a much better fit.

Therapists also have supervisors. Its their job to deal with these types of problems so there is no need for you to confront him. All you need to do is put in writing what happened and submit it to the supervisor. Include the fact that you are afraid and intimidated by the thought of what he may do because of your reporting him. The supervisor will see to it that he does not threaten or harm you in any way.