Before any skills, one piece of understanding: what is happening in you is not damage. It is a survival system doing its job, stuck on. We won't go near what happened. We are only going to understand the system it left running.
When something overwhelming happens, an old part of the brain does what it evolved to do. It puts everything into survival. Heart rate up, muscles ready, senses scanning, the thinking brain mostly offline. In that moment the response is working exactly as designed. It is what kept you going.
The trouble comes after. The system is supposed to switch off once the danger passes. After trauma, it often doesn't. It stays on, primed, still scanning, because as far as it can tell the danger might still be here. Stuck on, not broken. Loyal, really: it is still trying to protect you from a threat it believes is out there.
Survival is not only fight-or-flight. There are four common shapes, and none of them is a choice you are making:
You might live mostly in one. You might move between them. All four are the same system, protecting you in the ways it knows.
If you believe your reactions mean you are weak, damaged, or overreacting, you end up fighting yourself on top of everything else. Seen plainly, a jump at a sound, a shutdown in a crowd, or a flash of anger is a survival system misreading safe for dangerous. A system doing its job too well, not a fact about you. We work with that stuck system gently, and never by taking you back through what set it off.
Nothing has to change this week. When a reaction comes, see whether you can name it as the system rather than as you. "That's my survival system, not a fact about me." That noticing is the first inch of ground.