Yay, a forum! (And thank you for making Facebook *not* mandatory!) I would keep acting professional and keep the line moving without getting into a verbal or physical confrontation with the woman. If she and the crowd continue to do what they are supposed to do despite any grumbling, I would ignore it, but if they start getting physically pushy with me or with each other, I would request assistance from those with authority to deal with unruly crowds, and also get myself to safety first if necessary.