I can identify with experiencing terror etc while still being aware of the here and now - most of the time that is how it has been for me. It is very peculiar, but I think I prefer it to the total immersive sort of flashback.
You mentioned how you can't just say how things should be, like not blaming yourself, and find it works - I know what you mean. But over time I have found that repeatedly reassuring myself about something can have some effect, over time - when things are feeling grim it still doesn't help much, but in the in-between times it has started to work a bit. It's very hard when all I want is for it to somehow be ok, totally and completely, but at least there are times when it isn't quite as bad.
I'm so sorry you are having to deal with this, (((geis))). But even when you can't make progress, just keep standing as much as you can.

Bluegrey