Regarding Facebook: for totally different reasons, I recently temporarily deactivated my Facebook account, with the intent that I will occasionally log back in to check things and keep old photos etc. on there, but most likely have my account deactivated most of the time for privacy reasons. Not sure if this is relevant to your situation, but if your concern is wanting to hold on to memories/old photos etc., you could consider something similar. As for the long explanation thing: I don't think you owe anyone a justification for who you are or the timing of when you realized that you you are trans. However, if you want to share that with people and think a long facebook post would simplify things for you or be cathartic to write, then by all means write something.
Regarding Facebook: for totally different reasons, I recently temporarily deactivated my Facebook account, with the intent that I will occasionally log back in to check things and keep old photos etc. on there, but most likely have my account deactivated most of the time for privacy reasons. Not sure if this is relevant to your situation, but if your concern is wanting to hold on to memories/old photos etc., you could consider something similar.
As for the long explanation thing: I don't think you owe anyone a justification for who you are or the timing of when you realized that you you are trans. However, if you want to share that with people and think a long facebook post would simplify things for you or be cathartic to write, then by all means write something.