Just a few things that I am going to want to make sure I don't miss and can make sure I convey the message correctly. Some people will need tweaking on the script of course but in general many of the points will be made for each person. Most people will likely be told in person but I am considering writing a letter as well to many. It may depend on how I feel about the situation which method I choose for them.
I have something important to say. This news may change your opinion of me for the better or for the worse but I would respectfully ask that you let me finish delivering it. I have been repressing my feelings and myself for a long time. Recently I made the decision that this would stop. I am going to be the version of myself that I want to be. I am transgender. I am on female hormones already and have been keeping it from everyone for a while now. In this time I have felt that I am betraying you and myself by not delivering the news.
You are an important person in my life and this all may come as a shock. The information I have just shared is a statement and is not something that will be debated. I will answer any reasonable questions you have. I am open to talking and will do what I can do help you understand if I can. Things may be weird for a while but change is not easy. This is a big change for both of us.
I understand that you may feel differently about me now. I am no longer hiding this from you and you can now make the choice to stay in my life or stop associating with me. I cannot control that but I am in control of my life and this is where it is heading. It is important to know that even though changes will be observed I am still the person you've known. I may change physically or display qualities that you have not seen from me but it will finally be the true me you are seeing.
By this point you may be in shock or you may have already made up your mind. If you want to continue our relationship then not much will change. If we are going our separate ways then this is better for both of us. I do not want to include in my life those who do not want me in theirs and I am sure you will feel the same.
Reasonable questions that I have some answers to now.
Unreasonable questions that I will not answer.
I am fine talking about the topic in private but in public I am not. If you are still a part of my life I will share with you the other people who know so that you don't have to question whether someone does or does not know yet. I am okay with some joking but understand that I may not be okay with it. I trust you can use your best judgement and I will use mine. If there are issues I will try to be as direct as I can with you as to what they are.
I had thought to put links in but really if they are getting a letter it's going to be printed and you can't click on that.
Here are some anyways:
http://freethoughtblogs.com/nataliereed/2012/04/17/the-null-hypothecis/
A comic that explains how it feels: https://i.imgur.com/DZXGmsf.png