I would not have the meeting with your T and family members until you have time to plan for it adequately with your T. It may take a couple of sessions to get ready. Also, does your T think this is a good idea and will be helpful? If you decide to go ahead with this, work out with your T what the "rules" will be. Perhaps most importantly, do you really want this joint session? Or is it your family's idea but not something you really want? If the latter, then don't feel pressured to do it. Instead, you could work with your T on improving your communication skills so you could communicate with your family better outside of therapy.

I did bring my husband to see my therapist with me for 9 sessions. We didn't have rules, but my T did warn me I might feel abandoned at times and that some clients can't handle it. He reassured me beforehand that he would not be abandoning me, that he would be right there, even though he was talking to my husband. Just to be patient and he would get back to me. And if I did feel in need of more connection with him, to let me know, and he would give it to me. Even with these warnings of what to expect, there were tough moments.

Also, you didn't say the relationship of these family members to the abuse incidents. If any of them were involved in the abuse, go over this carefully with your T to make sure it is a good idea to meet together.

Good luck.