Hello prof_x: I don't know as I have any particularly useful suggestions for you here. But I noticed no one had replied to your post. So I thought I would.

I don't know if you see a therapist. My impression is that anyone who is transitioning probably should. The thing is there's just no way to tell what the reaction from family & friends is going to be. They might surprise you & be really supportive, they may freak out & disappear, or they may try to just avoid the whole thing... pretend it ain't happenin'... From the transition videos I've seen on YouTube (I've watched a bunch of them) it seems like writing a letter is a popular way to go & has met with some success. You mentioned you wouldn't be seeing your sister soon to deliver it. But could you not mail it?

I don't have any first hand experience with this. I struggled with gender identity issues most of my life but never did anything about it. It seems to me, though, that going the letter route could be a good way to go. It gives the person you send it to time to absorb what's happening & to calmly consider what their response is going to be. If you make the announcement in person, there's always the possibility that everyone involved will be carried away by the dynamics of the situation & that things will be said that will be regretted later. Of course, that can happen with a letter too. But perhaps that is at least somewhat less likely. Perhaps a letter to be followed-up with a timely in-person visit would be one possible way to go. Anyway... these are just my thoughts with regard to your concern. Good luck!