I don’t sense that he has had anything but a feeling for this woman maybe not as deep even as he thinks it was. I felt she was pulling him away from his family. I would continue to work on the marriage and if you forgive him and want to move past this , then it doesn’t even matter if they were sexually involved. You forgive period. However I sense the guilt he feels and he really is sincere in wanting to put his family back together again. Thanks