@Zanie, those tattoos in your userpic are beautiful! Wow...
@noob: I've been in your shoes, in so many ways. I spent all of high school having feelings for guys I wasn't dating, and assuming it meant there was something wrong with the relationship I did have-- ugh! Then I found out about poly two years into dating a guy with a really high jealousy quotient... I tried to open up that relationship, with spectacularly explosive and unpleasant results. (Seeing others' responses on here, I wonder how often opening up a relationship really does work... I'm not trying to discourage you, but I am concerned about the phenomenon.) Given that cheery bio, it's worth stating that both that partner and I are in happy relationships now, though not together; mine are even poly relationships!
Since your husband tends not to be verbal about these sorts of topics, I wonder how else you might engage him. If he takes in reading better, there's a few threads around here with books and articles. Here's a recent Boston Globe story that's been pretty highly recommended and that I like a lot:
Beyond that, the best advice I can give you is to point out that, as much as the people on here know about poly and their own experiences, you're the one who knows your husband. Let that knowledge guide you, and good luck!