New to this. Is it really MLC or just an affair?

[Lone77]

I spoke to him about counselling, I've been attending on my own after he convinced me initially that this was my fault. He told me in November/December that he knows he's in some sort of crisis and needs help but still hasn't sought it and I know that I can't make him do that until he decides to do it for himself. He's always been complex, has always said I'm his best friend, no one understands him apart from me and people always commented on how together we were. Our D is in her final year of high school before hopefully university, the girlfriend he has is only 6 years older plus they share the same name (uncomfortable). He lost it with our D when she visited his apartment for the first (and only time) as he won't let her have her say about how disgusted and disappointed she is. He's destroying his relationship with her and says that he knows he can't be in my future given what has happened but the thought is so painful. He's sent me song lyrics and claims to have told the OW that he's struggling without me although given the gifts he's buying and money on travel she's sticking around.
I believe that if there are problems people should at least try and work them out, at least then the scars shouldn't be as bad and everyone knows they tried. This time last year we had an shaving holiday together with fantastic chemistry but then the ILYB, life's too short, is there more to life than this etc. Yes we got together young but it's never stopped him from doing anything, I've always shouldered most of the responsibility within the relationship and he travels a lot with work. We've also been fortune financially with amazing holidays, a lovely house and cars, to everyone we had everything and approaching our D going to university this should now be our time. We had plans to move and all sorts, he says this was just settling, believing it was ok just to be ok. He doesn't seem to be able to separate real long standing love for infatuation. At 38 I've dedicated my entire adult life to this relationship. I feel so useless as I know I can't help him make sense of it and he feels how he feels currently.