I say again that the best way to handle someone who is personalizing and potentially bullying is to call them on it in public, right where it happens, so the person being targeted has the support of other members, and the person who is out of line has the pressure of social accountability to behave themselves.

Like someone said about being put in a room with an abuser, the private way just invites even worse and rarely works even if you try it.

I believe as a peer-run group the power of the community to respond is healthy and reminds people to stay in line. That's how real groups run. A little meta- or processing conversation is built in just in case something gets off track. It doesn't cause more drama; in fact it resolves things quickly because there are other people watching. Then you can get back to the discussion that was getting off track. It is part of almost every group to have this sort of mechanism so people feel protected and safe as a built in structure.

I'm just asking you to consider it and see how it might work to help things. You could set a limit of two-three posts that are slightly off track and allow that little amount of wiggle room so people can work things out for themselves. I think it actually reduces the potential for harm and drama to be more open to the idea that some processing takes place in certain kinds of discussions. Trust the process and the members to keep it going.