I have had similar confusion over what a "flashback" actually is.
I have experienced very few, myself - mostly like a body trigger related to a past assault, but while my body and emotions respond like I'm being assaulted again, I KNOW that it's not real, that's not what is happening. It's like even as I am "crying it off" or shaking it off, I'm aware that this is a MEMORY.
But I am the "supporter" in my relationship, and my husband has much more involved flashbacks somewhat frequently.
For him, it's like fragmented memories that surface so instantly - usually negative - without any preamble, and there is some signature fall-out after the fact. Inside the flashback, at least one part of my husband is thinking/seeing/feeling like a past thing (threat/attack/abandonment/relational offense) is happening RIGHT NOW .. It's not exactly "re-living" for him in the sense that he's in some kind of time-warp or holographic reality, but it is a LITTLE like that for that PART of him that's triggered. But there is usually some part of my husband who remains "present" (here and now) and aware that this "feeling" isn't "real-time" ..
My husband is a "multiple" so it might be a little different for him than other kinds of PTSD individuals, but it's like my husband's "present" self has to run after the "flashbacking" part and BRING that part back to the present moment.
This has happened with his "Grumpy" protector side - where my husband has to flood Grumpy with evidence/proof that this or that isn't REAL (ie: literally walking around the house and picking up things or pointing out things to himself - like, the door is locked, the furnace is off, there's no one on the porch, etc.). "Everything's fine," etc.
And this has happened with his "Little" side - where my husband has had to reassure his young part(s) that some trauma/loss is past tense, that doesn't mean it's happening right now, etc. With "Little" it has more to do with reassurance as to future hope - like, "THIS thing you're feeling right now does NOT mean that all is lost! Look, we're doing this and we're making this progress and we're aiming here..." He has to actually spell it out, "Just because she (meaning me) said xyz doesn't mean it's just like your (Little's) mom when SHE said xyz...."
The keys for him to navigate are mainly to stay "grounded" (engage the 5 senses to get his feet back under him) - which can be VERY hard when you're in the middle of it. But it's like he's throwing a lasso around the errant emotion and hauls it kicking and screaming right back to "reality" where he can get a handle on it .. That process can take minutes or days, depending on the severity....
~WU
