Traumatic memories in the brain are like an overstuffed closet. You slam the door and try to keep them all locked tightly inside but every time anything jars the door open a crack they start to spill out. In therapy, you are opening those doors a bit at a time. Then you deal with what falls out first but there’s still the rest of the pile behind those ones. So you open the door a bit more and more spills out, and so on.
It is difficult work but the more you keep pushing forward the closer you get to being able to open the door all the way to an uncluttered closet.