The first person I told was my ex, who.... seemed to take it well at first. Actually, he did, but when we would get into arguments use it as a way to demean me or just hurt me, maybe to avoid the topic of argument or maybe because I hurt his pride and he felt that that would be the best way to get back at me. In fact when we broke up he kept asking me why I broke up with him and when I told him he emailed me back (long distance relationship, by the way) that at least he didn't "compensate for my lack of masculinity by taking too many stupid martial arts, hide behind pretending to be something I'm not" amongst other things about my economic status and time I spent in therapy for sub-clinical anorexia and other forms of general "not being good to myself" behavior. That sucked all sorts of balls.
There are lots of friends I've told, mixed reactions.
My little brother reacted with a total, "so.... you're a dude.... but like dudes....." long pause of confusion, followed by total non-interest. A year later "wait... so that means you can help buy clothes that will help with getting chicks! What do you use on your hair, how do I get it to do that spiky thing in the front?" I love my brother ^^
And then my Master at Taekwondo straight-up just asked me if I were gay, and because he's my master I felt like I couldn't lie to him and told him "kinda.... I'm actually trans.... but I like mostly dudes." I was pretty scared, I mean close-contract sports and such are not always the easiest places to find acceptability, and he's reaction was basically "that's kinda confusing, so do you mind that you're answered up to as 'ma'am'" and that was about it. I don't think he has any idea how big of a deal it was he was so cool with it.