I see lots of fear and anger coming out of your H. He is making threats that he may, or may not follow through with. If he will divorce you for "exposing" her, he will divorce you anyway.
Only he knows what he is prepared to do.
It's up to you. Think about it. Be calm, and work with your social worker friend. Do not act in anger, and although it is hard, do it for the right right reasons, not for revenge.
From all that you have written, your H seems to be involved with a mental health care professional that has committed a huge ethics breach. I can identify somewhat, because my H was involved with a woman who was a nurse. I was being treated for cancer, and she was trying to "help" him adjust to my illness. Uh huh... eventually I discovered that the "adjustment" process included weekly visits to a seedy little hotel.
When I found out the truth, my H made all kinds of threats. I thought about the kind of person that would do the kind of thing that she had done, and I had no problem with exposing her. It was rough, and my H was "angry", but what the heck, he was angry anyway.
Months later, he said that although it takes 2 to have an A and he is just as much at fault as she is, he felt that he was vulnerable at that time of his life, and she pursued him. It was probably the weakest time of his life, and she was there to be understanding, healthy and sexy. She also had 4 kids and was very unhappy in her marriage. She saw what a wonderful caregiver my H was and wanted what we had. She targeted him, and the man that I thought would always be faithful, my best friend in the whole world, turned into someone that I did not know. Ugh!!!!
From reading all of your posts, I can sense that it is important to you to know the truth about their relationship. It was important to me too. Some people can turn the other way and move on without lifting that rock. I could not. My H feared that telling me the truth about his A would end our M. But it hasn't.
Hold your head up and do the right thing. It won't be easy, but believe me, it will eventually be worth it.
Most of us are about as happy as we make up our minds to be.
