Nic, I don't think you are the only one that is feeling attacked here. We cannot base our opinions of what is going on with others on one experience. OT's H's experience with his XW does not explain away our H's behavior or the OW's either. Our H's are so confused don't think they really know what they are doing. My belief (which I won't try to push on anyone else) is that Satan has a hold on my H and that is why I pray everyday for his salvation.
Take care, Nicola. It will get better but it just takes time. Your H's OW is more than likely needy and insecure, especially now that she has met you and knows that you are no monster.
Everything happens for a reason, maybe Dad needs to find that it isn't better out there, he needs to realize how good he had it here. Maybe he will find God and that is the most important thing when he finds Him he will know he is supposed to come home.