I found the reaction from trans activists (especially allies) more revealing than the article itself.
Apparently, the author had no right to write this article, even with her ex’s permission. Some TRAs think it should have been written by the ex instead, as “it wasn’t about her”, while at least one trans ally thinks the subject wasn’t worthy of an article at all. In particular, the author shouldn’t have shared any negative feelings, such as sadness for the loss of the future she’d hope to share with her ex. Apparently, this was very transphobic.
So much for the importance of respecting other people’s “lived experience”, eh? Heaven forbid that a support human should forget her place and tell her side of the story.