My advice differs a bit.
If you were a couple who had only been together a couple of years, I probably would also echo statements about 'fixing what you have, before adding in a third,...etc,..etc,.."
...but you are not. 14 years is a long time. you declare that you both love each other very much. I don`t get the feeling that 'love is lost'.
I have to go with my hunch.
I think by reading your posts, you are EXACTLY where you should be. On a neccessary path of new self-awareness, self-discovery, and the most important aspect of all,..STOPPING THE 'BLAME-GAME'.
There are people in all walks of life, that never, ever get that through their head. Even in supposed 'poly' relationships. They are always looking to blame others for their troubles. You seem to be accepting who you are, and your responsibility to yourself,..and in return, you now see your husband in a much better light. DATS GOOOD !
Take it easy, go slow, and don`t get caught up in the 'romantic' notion of poly. It is definetly harder work, then anyone ever thinks. But, by all means,...EXPLORE.
If you are 100% honest with the people you meet, people can then make their own decisions. Do keep some rules of engagement in play between your husband and yourself, so that the relationship keeps progressing to a better place. Until you got enough 'good' history again with each other, make sure you keep your husband a focal point.
Oh, and one more thing,..don`t be to sure that your husband and yourself won`t end up being sexually attracted to each other in the future.
,...Life can have some mad irony about it. One of those never-say-never aspects can definetly happen, once you feel your current desires being met. Then 'directing him' won`t feel like such a chore.
There is always a flip side, in that we crave harmony and balance as people. What is frustrating for you now, can very well become fun in future.
Keep exploring, and looking into yourselves, and enjoy the gems that it brings you. Good luck.