I came across this article, and while it doesn't mention PTSD, it does talk about how for some people writing things out may work much better than talking them out.

So, writing a narrative, even if part of that comes out here in the PTSD forum, can actually work better than sitting with a therapist and talking out one's personal history.

Personally, I have noticed that at different more challenging moments when a person is struggling through a cycle, they choose to try to write it out, even if some words are missing. I know I did that myself, I also tended to repeat thoughts unknowingly too.
However, by writting it out, I got so I had something to read back to myself too, in that I was able to work on adding more, or even understanding "what areas" I was struggling with too.

So don't discount writing things out, it could prove very helpful in slowly getting to that much needed narriative of finally being able to "verbalize" one's own challenges.

How the Brain Separates Our Ability to Talk and Write | Neuroscience News