I've never been to a dbsa group so I dont know how they are run. Doesnt sound good though. I have experience with nami support groups. They are peer led but the peers go through an intensive three day training and are usually people who have been part of the group for a while, stable and a good contributor. However, sometimes there can be people who come to the groups who are strong personalities and not all group facilitators handle them the same. Some are better than others but the overall rule that should be abided by is absolute respect for one another.
You might be able to tell I was a facilitator. I would have been very disappointed with myself if I had allowed a group member to leave feeling as you have. Perhaps you could speak to the leader and let them know how you feel? I would almost guarantee if you feel this way, other members do too.
The whole point of the support group is for you to leave feeling better than when you arrived. That is my opinion.