Hi Joss. First of all, for me, telling my son was the hardest part in all of this. It's a day I will never forget.
I just want to tell you this; please make it a point to tell your h to honor an agreement not to badmouth each other when you are telling them. It is very important. You want them to have a relationship with their dad. It's your job not to bring harm to it. That is not to say you should lie, but, this is between you and your h and they don't need to know all the details.
Having said that, whatever happens regarding their relationship as a natural consequence of his decisions you have no control over. But their relationship is theirs to forge.
I know that people hope it is a MLC as they see a possible end to it. It's really important not to look at it in those terms because whether he is in crisis or not, it doesn't change what you need to do.
I want you to know there is always hope as long as you believe there is.
When I was going through this I felt this way; I wanted to be able to tell my son yes if he asked (and he did) whether I did everything I could to save my marriage. I wanted to be able to look back and see that I acted with honor, dignity and courage.
As far as the affair, remember this. She isn't the mother of his children. She doesn't share the memories of a relationship and a family.
Their relationship is built on lies and deceit. It is a house of cards they will tumble one day.
What matters is you. What matters is that you love enough to want to try to save your marriage. What matters is that you want the best for your family. Those are what are important...and she is not.
Here's the truth of it. He is unhappy. He needs to look inward to figure out why. He is on a journey he was meant to go on and he is the only one who could walk it.
You asked if there were other MLCers who acted as he is. Yes, there are. There is no one size fits all.
He seems to feel guilty some.
Though I know it's hard, but, the sooner you stop trying to figure out what things mean, the better off you will be.
Take this amazing opportunity to figure out you. Become who you were meant to be. Leave them to their ridiculousness.