Collective decision-making (more appreciated as collaborative decision-making) is a circumstance confronted or faced when somebody collectively separate from the choices before them.
The decision is then no long-drawn attributable to any particular somebody who is a segment or part of the organization.
There is a number of things you could do you but the best thing you could do is to leave the situation and go get help. You should avoid getting into it because that could just make it worse same goes with being defensive. I hope this helps!