people change, as you yourself have come to realize you want something else, perhaps your husband does too, keep talking, keep taking bigger steps, you won't know for sure what he has to say until you let him respond to what you've said.
maybe he will surprise you, you never know. But even if he doesn't and he does decide you being poly is not for him, he still needs to know and you need to stop hiding, mainly from yourself. poly is very often not easy, but if its truly what you want, fight for it. the one's out there meant for you are waiting and will accept all of you, but you have to stop hiding so they can find you.
tell your hubby, let him decide if hes open to seeing where this takes you or not, and stop hiding, be whom your meant to be.