I agree with the others, here. The way you are describing your marriage it sounds like it is broken. I think your priority right now should be to get that sorted out as two individuals, and to set yourself up with your life the way you want it, and THEN work on future relationships, rather than trying to decide whether you want to "trade up" while you're in your current relationship.
MOST poly folk who aren't interested in cheating more than likely wouldn't even consider you relationship material until you have got your marriage sorted out (either fixed or ended), because they don't want the drama of being around during a marriage break-up. Also, it adds a whole new set of distractions to the things you and your husband need to get done.
It sounds like from what you wrote that you feel like you have to be with someone, and that being on your own isn't an option - why do you feel that way?
Please check out The Birdcage - an open, friendly Polyamory forum for all parts of New York State
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