What you are describing is known by DID therapists..I hope you have shared this with your therapist, if you are under the care of one..the mind is wonderous and creative in the face of overwhelming emotions, memories, if it is survivable, mechanisms can be brought forth in the ways that to many would be "unimaginable"...

I have experienced the duality states you are sharing, and professionals have told me it is apart of the dissociative experiences for some..it is scarey, but not at the time, afterwards disorientation may occur, dizziness, numbness as you reground in your enviroment on a "one to one", instead of the duality.

Mine started in childhood when I would disappear into a wall in my bedroom, I had drawn a place some part of me would be safe and untouched, it had trees, mountains, a whole world would come alive, while my body died over and over again here..my mind would florish in this other place, where it could develop and maintain it's own reality.

I hope that you find comfort in knowing your not alone in the process your describing, from what I know about DID is that we tend to be able to get lost more in books, movies, etc, by the dissociative mechanisms...

I hope for you peace and comfort..