memories are lost because you dissociate while remembering them and that corrupts them, because whenever you remember something you kind of visualize / experience it again, but if you're out of it and don't re-live the experience when you access it, then it gets stored away as like a degraded version of itself with less clear details, and if you keep doing it, then all that's left are like the emotional reactions that seem to come from nowhere at all.

This sounds plausible, although it might be more that the emotional reactions overtake the rest of the details in the memory as they're the only thing that gets recalled. It could also be that the brain just becomes less capable of retrieving certain details about the memory, effectively eliminating details from the memory by misfiling them as not a part of the memory. Those details might continue to have an effect on thought processes, but the brain no longer identifies where the details came from.

Then again, I don't know that much about cPTSD in particular, so this is mostly what I know about memory more generally. Psychology doesn't know how this sort of stuff works with any certainty. It also doesn't understand stuff like divergent personalities and plurality very well.