My child was born a male. At some point began identifying as female. How long that had been going on before she told my wife, I don't know. But she wrote a letter to my wife because she wasn't sure how I would react. I was a little surprised by that, honestly. I wrote her a letter in return making clear how I felt and that she had my unconditional support.
It was awkward and challenging for a little while to adjust to female pronouns and to her new name. But it has become easier. Although before and after I use "kiddo" more than her name....
...I think I handled it semi-poorly not in my actions towards my daughter, really, but because I didn't really know what to do or how to relate. It has changed our relationship. I'm honestly just a lot less certain on how I should parent. I'm less of a disciplinarian than I was. My wife, on the other hand has embraced it more than I have, even still.She takes our daughter to get her hair dyed, nails done, buy clothes, etc.. She found a transgender youth support group for her and she has met most of her current friends through that group. So in a way I say I could have been better because my wife has been better. But this hasn't been easy for me. Like I said, I wished it would just go away. It wasn't something I wanted to deal with at all. It wasn't something I expected people I knew would really accept or understand. So I haven't talked about it openly until now.
I have a lot of the same feelings that all decisions should be taken carefully. I think there have been people who have identified one way and then identified another way and then sometimes identified some other way. I have no idea how common that is, but I thinks it's enough of a reason to be very deliberate in how a person deals with this type of thing. That said, my kid is nearly 18 and will be able to make her own decisions.