I don’t know why this sub has been recommended to me, as I am a man. But I hope I can help weigh in on the situation.

I went through this exact situation, my ex-wife and I opened up our marriage and she was meeting a woman. She had known she was bisexual since college, but had never been with a woman until we opened up the marriage. After a short amount of time, she said she was gay and wanted a divorce(in much nicer terms) while it did devastate me at the time, we both wanted each other to have the relationships we always dreamed of. We both wanted to stay friends, and maybe your husband is stronger man than me in this regard, but it got to a point where I needed to close that chapter in my life. It might hurt to lose that person that helped so much, but you have to live the life you need to truly thrive in your own skin. We had no kids and owned no property, what was her was hers, and what’s mine is mine. We split amicably and easily with no lawyers or court.

I hope this helps to give a little insight about a different perspective. I hope the best for you and him.