Art work, drawing the feelings associated with the memory, help decrease the dissociation and also help relieve the pent up feelings. Acknowledging the trauma and pain slowly can help the memory lose its terror. I try to negotiate inside that the memory will be shared slowly, since this is less frightening than the whole thing in its entirety, which can feel overwhelming. I ask if my alters can share the knowledge, or cognition, first, then gradually, over weeks, the visual and the feelings. I keep my promise that they will be allowed to share, I just ask them to slow the sharing down.
Good therapy can help tremendously here.
Take care of myself. This means slowing down, if I am taking on too much or am overly stressed. It means eating nutritiously, exercising, and getting plenty of sleep. I ask Jesus to comfort the parts inside who are afraid and wounded, and to bring healing to them. They often only feel safe when He is there, comforting them, holding them.