Through this whole time I am telling my hubby that I was having these conversations, downplaying the details of course and was surprised at first that he didn't have a problem with it in fact he encouraged it as it seemed to help our almost non-existent sex life (main reason we are going to couples counseling). One night, I half-jokingly suggested starting a "harem". And then I remembered some of the books I'd read being a sci-fi/fantasy nut (Friday bring the main recall) and realized that maybe this was a viable possibility. When I mentioned it to my hubby, he thought about it and then said, lets see what happens, figure out how it would work.
It is unfortunate that the relationship did not work out as you hoped it would. But the one thing that jumps out at me is the fact that both you and your husband came alive with the "poly-possibility." The fact that you two agree on that could well be a solid foundation for a very exciting and love filled future.
Barry