EDIT: Right, I see your reasoning in another comment. So, if I understand correctly, you believe that due to having agency in that situation it lowered stress and fear levels below whatever your threshold for (severe) trauma is? That's sounds plausible with my understanding (but I'm also a layman on the subject).
Wordsmithing is hard lol.
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I think it show great... something, but nobody is sure what. Maybe it's emotional resilience, or something neurological in how your brain processes fear and memories. Maybe it's a combination of those—and other—things (since they can be related).
I'm saying this because I think saying "because I stood my ground" is a dangerous message to spread around, though.
It also does a lot of people a bit of disservice because many who have PTSD didn't get it through inaction. Firefighters get it, soldier get it, doctors get it, etc.
Also, least time I read, current understanding—even if not great—doesn't support your claim that actions during the stressful/traumatic moments are relevant (at least not to the degree you make it seem). There's some small evidence that feelings of helplessness has an influence, but it's inconclusive since helplessness just manifests extra stress (but not the majority of it, and it's not universally present).
And finally a disclaimer for the above: I have zero qualifications on these subjects. I've always been curious of it because of my traumatic past having lived with CPTSD most of my life (not PTSD; they're different, but they have some "mechanical" similarities). So, I've read a few books on CPTSD and PTSD and healing from them, but they weren't academic literature.
I'm glad you came out okay from that situation, though.