Siobhan, thank you for your thoughtful comment, and especially for that link. Wow! I had to break that one down into chunks to digest! I appreciate that it’s more than just opinion, and that studies are linked.
I have found a therapist for my child. It was the first order of business 12 hours after the news. I found a WPATH certified Ph.D. who specializes in gender dysphoria. It took some fighting to get my insurance to cover the service in-network, but we’ve now visited five times in 7 weeks, and we’ve attended a support group in person for trans people and their families.