Pffft I am very willing to talk about what ever you want.
I'm glad you're acknowledging the incremental steps theory that your H didn't become like this a fortnight ago. I absolutely believe that his porn use has had a corrupting effect, in the literal use of that word, not the hysterical connotations applied to it.
I suspect the solo porn use led to the forum, but because you seemed to be cool about that (and porn generally), it's almost as though he'd received "permission". I am a stickler for language and what it means and I reiterate that the statements on discovery are very telling. "I felt I should have been allowed to say those things to this woman.." "There was no-one stopping me..." et al. This is all about giving oneself permission and feeling entitled to do it.
The flirty forum was a major boundary crossed in your relationship and the stuff you post about the swinging sites is illuminating. It strikes me that because the forum members seemed to be perfectly acceptable, this was a further permission-giving process...i.e., they go to swinging clubs, so it must be okay.
It sounds as though your H might be someone who needs someone else to validate his actions - you or the forum members.
I wonder whether this crossed over into your everyday life, whether he is someone who rarely makes a decision through his own convictions or after original thought?
Now I want you to think about something else. Somewhere along the line in the last 20-30 years, it has become "uncool" for women to object to porn. Various myths surround what motivates the women who have the confidence to dislike porn, either on personal or political grounds - and judging by the Mumsnet boards, many of them are peddled by women themselves.
A horrible stereotype of a woman who has low self-esteem/body issues and dislikes sex is trotted out, whenever a woman has the confidence to assert she objects to porn.
I wonder whether any of this has shaped you Pffft and your own use of porn?
Loves and I had a similar conversation about our feelings about unsafe friendships and the compulsion to be "cool" about an extra-marital friendship that felt threatening, with the result that the friendship threatened everything. It's the same principle in action here, trying to be someone who is laid-back, confident and self-assured - but there is a dissonance, because I wonder whether deep within you, Pffft, you had a nagging voice about that forum and the porn? A voice you tried to ignore because it didn't sit well with your view of yourself as a confident, self-assured woman?
Can I challenge this and say that the woman who states her boundaries and isn't afraid to insist on them, is the really confident woman.
I agree with Loves incidentally that he might be misinterpreting the Relate counsellor's words, but equally it wouldn't surprise me, because Relate has got a long way to go in understanding infidelity. Some of the therapists are more evolved and read more widely, but too many of them peddle the pernicious myth that there must have been something wrong with a marriage for it to happen. I'd advise him to switch therapists pretty bloody quickly, because this is a man who likes validation and permission.