has anyone heard of or utilized a trauma processing therapy technique as follows? I think it is similar to an exposure therapy-but a bit different,

This week my t gave me a piece of paper with a timeline in which I was asked to write bullet points about what happened during a specific incident. After that, I was given a paper divided in half and was given 5 minutes to write a detailed description of events leading up to the incident in the first half and then I was given 5 minutes to write a detailed account of what happened after the incident in the bottom half. I was then given a paper divided into 6 squares. I was asked to draw the parts of the event in each square but I had to do it by drawing the first part in the first square then the final part and then fill in between the two. I could only draw-no words or letters. THEN I was asked to used the drawings and tell my t the story-in detail-step by step. Through out the process he reminded me to breathe deeply. to relax so I can activate my parasympathetic nervous system. Finally, He had me sit up straight and breathe in deeply and exhale in a slow, controlled manner while he told me the story.
It was almost unbearable to listen to him tell me the story. Bt that time I felt like putting my hand through the window. At the end I took a few minutes to regroup and we ended our session.

I was wondering if anyone knew how/why this worked. I understand the parasympathetic nervous system part, but why is it done in so many different steps?