I'm going to have to come out to my parents fairly soon as genderfluid, which means I’ll also have to explain that I’m trans. For some reason avoiding the word only pushes me back into denial, but at the same time I recognise that “trans” is quite a loaded term for many people. So for those parents whose children have come out to them as being not cis in some way, what were the things you wanted to know immediately? It’s not that I don’t want to answer my parents’ questions, but I’d like to cover the major ones first in my letter to them so they don’t get unreasonably worked up before we have time to talk about it.
I think maybe just write what you feel are the most important facts about your gender and explanations then tell them the rest in person. It's really hard to predict what questions they will ask and too much information at once could be overwhelming.
it doesnt matter how you think your parents will react. you need to let them know you are certain about who you are, and there is nothing they can argue to change that fact. whatever the case, be confident and honest.