Friend coming out issues

Okay, so right now almost all the people I genuinely care about know about me being trans and, thankfully, most took it quite well.
However, there is still a bit of a nagging issue with my five oldest, and possibly even best friends. (though I don't like classifying anyone as a "best" friend, cause I all love ya' equally much for your own strengths and weaknesses!) Well, no matter whether you'd define them as "best" or not, they are still VERY GOOD friends, and we've been through an awful lot together. Needless to say, I do not want to lose them. And well, the issue is... THEY, out of all people, do not know yet.

Why have I "waited" you might wonder. And the thing is, I haven't. In fact, I desperately TRIED to come out to them more than a year ago, but wasn't ready yet, took a completely wrong approach, I failed, and never dared to confront them with it again. It went like this...

More than a year ago... I really wanted them to know, but also didn't feel strong enough yet to tell them in person or even simply send them an email or text. So instead of being a wise guy and just letting it rest, I wrote a journal on my DeviantArt profile, knowing there would be a large chance they'd see it. It wasn't even directed at them personally, and yet just the MERE THOUGHT they MIGHT read it made my hands shake and my heart pound more than a call from the VU does now. (and that's a big thing!)
They DID read it, as I suspected, and even left comments saying they'd talk to me about it next time we'd meet in person.
The stupid chicken as I was, I waited for THEM to take the initiative the next time we met up. I stimply did not have the balls (pun intended) to confront them myself. They did the exact same thing (can't blame them) and waited for me to take the lead, so... nothing happened. They must have assumed it wasn't important after all and I just put it away, not daring to bring it up ever again.

After that we just went on as if nothing happened. I knew they knew and they knew I knew, but it's like we both silently agreed to avoid the matter. That was all doable and good for me, after all, it was still very surrealistic in my daily life anyway. I still lived fully as a girl.
But now... things have changed. The wheels have been set in motion, I'm actually taking steps to become the guy that I am, I am being seen and addressed as a guy by my classmates and new(er) friends, and this whole trans thing is becoming much more REAL as for lately.
This makes that the feeling of "acting" and "lying" to my five old friends has strongly increased, SO MUCH I often just don't want to meet up anymore, don't want to hang out... (when we are it is, except for the constant "girl(s)"-ing and misgendering, great fun, and I realize I don't want to lose them. Ever. They mean too much to me. But I'm afraid I WILL lose them if I don't do something quick!)
Though as the days passed... fear of rejection was replaced by feelings of guilt, because THEY are five REALLY GOOD friends, and I haven't yet told them. They should have been the FIRST. And each day I feel like telling them is getting harder and harder.

I'm also going on a skiing holiday with one of them, and I feel like I REALLY have to tell them -her at least- BEFORE we go. I can't be stuck with one of my friends for a week and be misgendered all the time, and act like "all is fine", cause I KNOW beforehand that will drain me more than any amount of physical exercise. I'm very afraid they will feel... insulted, for only hearing it so late, though. But only time will tell.

(I also wrote a blogpost about this when it happened (the failed "coming out") which can be read here: http://thetranshippie.blogspot.nl/2013/07/weirdest-reaction-to-coming-out-ever.html)