Advice for coming out to someone who you're pretty sure won't accept it?

Hey all,

This is still a bit of a ways off but I'm asking now because it's really been plaguing my mind the past few days.

This summer I'm starting my Hormone Therapy and around that time I plan to come out to everyone. Most of them I'm either not sure how they'll take it or I know they'll react like my mom (who just is in complete denial and cries if i bring it up).

But two people -- my youngest brother and my grandfather--I'm not sure how to approach.

My little brother has reacted badly to the reference of Trans people to the past, and we never have heart-to-hearts so it'll be doubly weird for me to talk to him about this. I was wondering if any of you had any advice how to break it to him gently without him getting mad that he was the last to know, which is my biggest worry. My middle brother and my mom already know. Also a letter is out of the question as he won't bother reading it.

My grandfather I'm well aware that he'll probably stop speaking to me or just get really really mad and call me a lot of awful names. That's what I envision happening anyway. He doesnt have a computer and the idea of telling him in person is terrifying so i thought I;d tell him by phone, but I'm worried that I'm being too cowardly in doing that.

Any thoughts or opinions would be awesome.