I just recently started to come out to the people I care about and I have honestly been blown away by out accepting and supportive everyone has been. I knew I had some good friends, and I expected them to at the very least 'not care', but everyone has been super happy for me, and glad I'm figuring things out, and very authentically genuinely amazing.
What telling people has taught me is that you can usually trust your gut instinct. As worried as I was that everyone was going to freak out, I was still pretty sure they wouldn't. And After doing this a few times, each time they react better than I expect. If you feel like someone might not be open to the fact your trans, then be prepared for them to not be. but if you feel like you're surrounded by good people, then trust that they will be the people you think they are. They might just surprise you in the best way possible.
Good luck with coming out, when you decide to. It's tough, but it's worth it.