You can try and manage yourself not the narcissist. Say how you feel but do not go head to head cognitively. That is their strength.
You must not be too invested in their response this gives them power. Nor do you justify or get into a debate about your views or your decisions.
My experience is that you can't stop this narcissist taking over the group. All too often the group stand by the narcissist wanting their approval.
If you think this is where this group is heading start walking, its toxic. There are plenty of other healthy groups for you to join out there.
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