naivewife, You are no more jaded than any other BS who has been betrayed by her husband. This post may seem quite harsh - but you asked what people thought and here is my honest opinion - I don't know how to put it any way other than bluntly but please know that I'm not trying to hurt you, it's just my honest thoughts.
I think rather than you being jaded, it is instead that you are only now recognising this for the very serious problem in your husband that it still is and always has been. When you couple this post with some of your previous posts, most especially the one about your husband not knowing if he could stick with NC if the OW contacted him because of his feelings of 'responsibility' towards her, then I think you see how dangerous for your marriage this really is. There is a difference between being a good person and being one who is addicted to the feelgood factor of being a KISA which in my opinion your husband is. Especially a continually justifying KISA at that, who has already had a physical affair that included, upon discovery, putting his wife through a false R when he missed those feelings too much to let go of them. (Which by the way, he still hasn't if he tells you that he still feels 'responsible' for OW)
..and now he's back starting afresh to do it again with someone else, sharing again all that intimate and confidential talk between them about their inner troubles and feelings. Rather than seeing this for the huge problem that it really is and working to try to understand and change his need for it - he is actively trying to justify all of it away as it being.... 'Just who he is'
What I think is that a man 'Just like this' especially one who has already indulged in an affair, but wants to continue getting himself over involved with other people who have problems that need solving or feelings that need his validating, is a dangerous person for you to trust going forward. A man like this needs therapy himself and he shouldn't be someone trying to advise other people.
Who is this new person he's involved with and getting his feel good factor from now anyway? Is this another woman? Not that it makes that much difference if it's a man this time. Because eventually just by the law of averages it will come to be another woman and what then? If he doesn't start seeing his own weaknesses in this area, if he refuses to acknowledge the seriousness of it and worse if he continues to just justify everything he does with the words 'It's just who he is' then he will always be vulnerable to repeat his actions - with the past OW or a new one.
naivewife, without a doubt in my opinion this is an enormous cause for your concern. Without a doubt you do need to bring this out into the open preferably with a good counselor. I think this is so ingrained and so deeply seated because it's quite obvious by what you say about his mother that this is, again, without doubt, a foo issue and it does need to be addressed asap.
Sorry this is so harsh - but it's my honest thoughts.