Well, my husband called last night and finally after several attempts to contact them they answered. His brother never brought it up so my husband had to do it. His brother told him he didn't know what to do. That he's been friends with him for so long, but he didn't want to lose his brother either. He finally wound up saying that he didn't think he would stop being friends with the OM because of this. That was enough for my husband. He sat there stunned in silence for a minute and then said goodbye.
In my conversations with my husband he told me that even if he had decided not to stay with me that he still wouldn't want to have a relationship with his brother if he was going to remain friends with the OM.
His brother lost all of the respect I had for him. He turned his back on his brother. It really hurts, but our relationship with them is over.