If you haven't already given the letter to your mother, consider this. Leaving a letter as opposed to face to face has both advantages and disadvantages. One of the disadvantages is that if your mother doesn't say anything about it, you will be in a limbo of not knowing whether or not she read it. It does give her time without pressure to think about it, but it also leaves an empty spot in which she will form her own ideas of what a transgender is.
Face to face can be uncomfortable, but you know that she has gotten the information and the lines of communication are open immediately. You have a chance to answer questions right then and there rather than letting her form her own answers.
You know your mother better than I obviously, but consider both if you haven't already.
sam1234
