This is by far one of the most imporatant an significant feeling you can have for entering into the poly lifestyle, IMO. (I don't speak for all)
What I find, is that by opening your heart, and putting your feelings out, you have established that regardless of his actions, you will still love him.
Next, you have to flip the coin, and decide whether you can find other loves to share your heart with. It might be your children, or other family members. I could be another man, or even a girlfriend; but to me, poly is sharing love, not just fooling around behind someones back. When I say love, I mean love; not sex. How do you know the difference? Easy. Would you run into a burning building to save someone you only had sex with?
You have established a trust that goes beyond the standard boundaries of monagamy, and begins to establish community. I see this as the strong part of poly. Have you noticed the lack of community in today's society? Gang activity? Road rage? Random violence? Apathy? Unkindness, and even abuse of strangers? Poly might not be the cure, but it is a path of potential relief. Just my humble (and honest) opinion.
Welcome to the site.