How do I stay calm when kids get chaotic and I'm scared?

You keep children safe. Most of the time you handle it well, and then a moment tips into chaos and the fear grabs you. That fear is not a flaw. It is the sign that you understand exactly how much is at stake. People who feel nothing in those moments are the ones to worry about. The goal is not to stop feeling afraid. It is to have your hands know what to do while the fear moves through you. That comes from having a plan you have rehearsed so well it runs without thinking. When the moment hits, you fall back on the drill, not on nerve. So pick the chaotic moment that scares you most and rehearse it when everything is calm. Walk through the exact steps, out loud, more than once. When it happens for real, your training carries you and the fear becomes just noise in the background. You are already responsible enough to be scared. Now give that responsibility a plan.