I'm a relative newbie to all of this myself, but I just wanted to jump in and say that whatever you do, I would not let the notion that this always has to be kept a secret hold you back from pursuing what you decide you want to do. It was a lightbulb moment for me when I realized that (for me, at least) polyamory was not something that I had to keep "behind closed doors." If you find yourself in a serious, emotional relationship with two people, there's no reason why that can't mean eventually "coming out of the closet." I'm (almost) totally open about my relationship with my BF. My friends have for the most part been supportive even if they don't fully understand it, and if they were jerks about it, I would consider that their problem. In public and with more casual acquaintances who know that I'm married, I still act openly like I'm with my BF if he's the one with me. If people want to ask what the situation is, I explain it. The way I see it, I don't want to treat one of the most important relationships in my life like a dirty little secret. It's a real, valid relationship, and I treat it like one and expect others to as well.
I'm not saying necessarily rush to tell the whole world, or that you won't at times feel a lack of being able to talk to friends the way you would about a more "conventional" arrangement, but I also wouldn't take it as a given that embarking down this path means you must always be hiding something. I would worry about what you want as far as the actual relationships are concerned, and make your decision based on that.