Can't add a lot to what the earlier posters have said except to say that you are definitely not alone. I am in the same position as your husband, let me repeat that your acceptance and tolerance will have humbled and amazed him, as my Dory's did me. It is quite something to be loved that much.
What you might not have quite internalised is how much of a liberation poly can be, if like me you have been repressing it for years. I find I can better express my love for Dory now it is free from the implicit exclusivity, and in many ways appreciate what we DO have, now I have ways to explore the things we don't share, and probably never could.
I sincerely wish you the smoothest possible ride to an open and honest set of relationships. Please keep posting from time to time so that others that follow you can see how things unfold for you.