background: I am driving home from college this coming Friday, and am picking up a friend (who attends a different college) along the way. I wrote her a letter because I will probably not be able to bring up the subject otherwise.
aand, aack! Scary things! I still don't know exactly how I identify or what's going on in my brain and it's terrifying!
But I have realized that if I don't do anything, nothing will happen. (ie, if I decide that transitioning is something I want to do (which right now seems like the right thing to do) then I'll actually have to start talking to people about it!)
So here is the first step:
------------
Dear [name redacted],
There is something Very Important that I wish to tell you-- although letter-form may be a strange medium to convey it, given that you are most likely sitting next to me in a car (if all has gone to plan and I have actually delivered this letter when I intended to.) However, I did not trust myself to words on this matter, and hope that this will suffice.
And as I do not believe that I can delay this information any longer, here it is: I believe that I am transgender. Where exactly I fall on the gender spectrum, I have not determined fully, but I know that I am not female. I have made a handy chart to illustrate:

            ________                                _________
             \ female /  --------------------   \  male  /
                \      /                                         \      /
                   \/                                               \/
                          \                                        /
                             \                                 /   <- I think I'm somewhere on this line
                                 \  _________     /
                                     \ agender /
                                         \      /
                                            \/



I don't really know where I'm going from here-- if/when I wish to transition or change my name or pronouns. I'm still fairly uncertain about everything (despite having these thoughts for several years.)
However, I believe that you deserve to know this. You are one of the people I trust most in this world, and I don't think I could ever express how much your friendship means to me.
And now, I believe I shall wrap this letter up, as I am most likely anxiously awaiting your response!
-Sincerely,
You know who*

*but not the evil-wizard type of You-Know-Who.** More like the confused friend who just handed you this letter type.
**probably
--------------------
end letter

ahhh! even just writing this all down was a bit scary... I'm not sure I'll have the courage to actually hand it over...
I guess we'll see in a few days

My first reaction is to lean over a give a big hug and I don't even know you.  Now I hope your friend does the same thing (as long as you don't lose control of the car). 

aha, thank you (although I do think that hugging might be a bit out of the question while I am driving )

I am feeling almost... optimistic about things ? It's been such a long time since I've felt positive about life. But I think I am starting to take control of my life and doing what I need to do.
And even though I'm not certain about where I identify gender-wise, anything that makes me feel like that must be a good thing, right? (aha, I think I'm starting to ramble )

Anyway, I guess we'll see how it goes tomorrow...