You're doing what you can, that's all you can ask of yourself. You're going slow, you're keeping everyone informed about what's going on with your feelings. They need to know that this is who you are, and if in fact it is, then it's as much a part of who you are as your gender or your orientation.
Every now and then, talk to them about it. Don't let too much time go between conversations about being poly (you don't want them thinking it was just some passing fad, which from what I see it almost never is). If they're good people, and not too terribly brainwashed into thinking it's mono or the highway, then they will accept who your are and not be threatened by it.
But most of all, go slowly. I think just about any love can survive change, as long as it's done at the pace of the most unsure person.
Take the risk of thinking for yourself, much more happiness, truth, beauty, and wisdom will come to you that way. - C. Hitchens
Me: Male, bi, 48, flexible