Op I think you may have posted before..... You have always sounded shell shocked, deeply deeply hurt, and sort of lost. Maybe stuck in disbelief and pain & indignance at the unfairness of what he's done.
While it is totally understandable.... he has treated you horribly and it is "unfair" .... and it it continues to be unfair that he forces you to be more or less a single parent to your young adult kids ..... You sounded like you need counselling, and that you also need to accept things about your husband and your marriage that you maybe didn't see.
Even now you're not really focussing on them, but rather on his current wife and her lifestyle and their life together.
It appears obvious that while you were invested and committee for life - as many people are when they get married - he was not.
When he decided he was not, is not clear. It could have been all along, it could have been in the latter years.
That didn't become clear til he started up the relationship with his current wife and then left.
It's also the case that he has several very shitty character traits demonstrated through this (and continuing to be) and it seems like you overlooked them/didn't recognise them .... Or if you truly never had any sign of them; that you haven't got your head around them emerging in recent years.
This is not even a "I don't want you be with her anymore, I've met someone I do want so I'm going" scenario.. his behaviour towards his adult kids shoes much more callousness and lack of integrity and responsibility and decency than just that.
Have you had any counselling?