Welcome Holdingontohope,
I think it will be great to clarify with your t what he meant and tell him how it made you feel. I know it can take a fair amount of courage so good luck! It sounds a little like these are things you haven't spoken about before or not much. Is that the case? That would be different to speaking about it again and again (not that we don't sometimes need to do that to heal).
The way I understand it and have experienced it is that talking (In verbal and written form) about it can be an important part of processing it and processing it is the way to heal trauma symptoms. There are somatic, art and other non talking ways of processing as well but moving the trauma from the wrong part of our brains, developing a clear narrative for it, and storing it in the right form in our brain in an integrative way is a major part of healing.
The way I understand and have experienced the potential harm of talking is when we are retraumatised by it (by speaking about it before it is safe for us to let it out; if we do not have enough of the support we need or the coping skills we need; if we are met by unsupportive responses or an unhelpful environment that reinforces aspects of the original harm; if we are rather reenacting and reinforcing the negatives of those experiences instead of resolving them). It may be that he was merely inquiring and gathering information about where you are with the trauma and what beliefs you have about it that could be unhelpful.
I also agree with Lola Nocheprieta that looking at all the minefields surrounding the stuff for us can be helpful. I have a lot of those anyway!
I looove your box analogy so thank you for sharing it. Is your t a trauma therapist? I'm assuming he knows the importance of processing trauma as a concept.