The woman is his "ex" because he left her, gave up on her, severed the relationship.... even if it was because of something she did or said, and his choice was finalized when he chose to marry another woman. When he married another woman he declared the previous relationship was over.

It's suspicious that he says they must speak in person face to face. How can the "ex" be demanding on how they communicate when they are no longer in a relationship?

My thoughts: We should do more to be reconciled with people while they are yet living instead of waiting for them to die. It would be good for him to confess his faults to both his ex and his wife to gain their forgiveness. He could give the "ex" the option to communicate openly with him, so that his wife could also hear or read what is said, but not privately face-to-face. He would hurt his wife doing so and could even fall into temptation in person and make matters even worse. A safe option would be for him to send the ex a written message, allowing the wife to read it first. If the ex is serious about communicating, she will compromise on the requirement for it to be in person and also reply in writing for the wife to also see.