I think you have to concentrate on you and your life; you can't orchestrate their lives, they get to do that. You have to decide if you want to stay married and work on that relationship with your husband if he wants, let the other person go, let the friend go, he does not belong in your marriage, ever/at all. If you don't want to stay married you can move on but they are going to feel their own feelings and have their own thoughts about you and each other and you can't do anything about that.