Well written. I understand. It is indeed difficult to explain, but the word "detachment" is a good word to include. Been there, done that, more than once, and two times that immediately come to mind there was an element of complete surprise on my part. Once I was shot by a sniper, and another I surprised a large bear in a place (but not moment) where I expected one to be. In the bear incident, upon seeing the bear, I reacted perfectly with my actions up to and through my first shot (which was a good one).............and then I "detached" as I watched him roll backward, spin, thrash,...............and then lope away.
Much later, back at work, a friend called it "buck fever". I disagreed, pointing out that my actions through the first shot (despite my initial surprise) were immediate and perfect, and he pointed out that "buck fever", which I never truly understood despite being a lifelong hunter, has no required timeframe. To this day, as you correctly write, I can't say he was correct or not, I can't adequately explain it, but it's very real.
Moreover, since 2012, when I drove my pickup truck through the ice and to the bottom of a large lake at 44' deep, I've also been dealing with PTSD in a very alert, expectant, and educated way. Unlike 1975 when I was shot and PTSD was still a psychological phenomenon newly recognized in Vietnam veterans and undergoing new, intense, and continuing research, I fully expected to feel its effects after my brush with death trapped in my truck at the bottom of the lake. I even knew what those effects would be since I had gone through them more than once before.
I'm learning that I knew nothing, but also that 7 years later I'm still learning that I don't understand so completely that my new experiences really won't be of much help to me or others. I'm quite confident that people who experience sasquatch encounters deal with very unique PTSD effects for the rest of their lives afterwards, and there's really not much they can do about it, even if they're wise enough to understand that they're going to go through it.
Suffice it to say that I now strongly believe that PTSD has a definite cumulative effect. Each time one adds another psychological trauma (and that includes emotional trauma like fear, loss, surprise, etc as well as physical trauma), your mental health dies that much more, and recovery might not be forthcoming. My PTSD, starting in my childhood and being built upon every few years since with fresh traumas, emotional wounds, fears, and even major disappointments have destroyed me, and hurt everyone around me.
I'm crazy to want to see a sasquatch. Maybe that desire says a lot about why my life is not much more than a collection of regularly scheduled traumas?