No stopsign so I hope this ok, me posting as a BS.
I read your story and the growth is so evident in your story. While I know this is not the result you wanted, but you are becoming a healthy person who will not pass this down to their children. Your life will be better, even if its sad, as long as you stay on this correct path you have worked so hard to get on.
You are also giving your BS a gift in how you are handling his decision. Again, I see major healthy in this. Giving someone the gift to live their life as they see fit is big. It shows respect for him. As a BS, that is one thing I struggle to see - my WH's respect for me. I really see your respect for your BH which speaks volumes to me.
Wishing you a healthy future, no matter where this journey takes you...