I wanted to add another thing, but I don't know if this makes me sound biased. We all screw up (platitude, I know) but the great thing in life is you often get to start over. The embarrassing thing you did in high school gets forgotten. College disappears. You fuck up really badly at a job, you get a new one and no one knows. Assuming no criminal charges are filed, most of the fuck ups in life can be erased with time. I think what makes marriage especially hard is that there is no do-over. A marriage is, in many ways, a never-ending accounting ledger of rights and wrongs.

And, for some reason, we seem to think that the longer we're with someone, the more they owe us their goodness. I gave her five years, I gave him ten, she gave me 27 years....it is a nearly impossible standard to live up to. In fact, making a really, really bad decision only increases in likelihood. I know the other side of the argument, which is that what you've built should be all the more precious. It should matter more, mean more, and you should be more faithful to it. I think that's true too. But I also think we're all living in the solitary confinement of our minds and even the best people don't always know why they did the thing they can't explain or forgive in themselves. Even you write, " I never thought I'd do this, I never thought I'd sink so low". No one does.

So, while you're pondering the philosophical disjoint here, I'd ponder that as well. What is marriage if not the long-term accumulations of slights and forgiveness?

Last point, I swear: if you do leave, you better have a fucking amazing cover story as to why. If your daughter finds out her conception ended her parent's marriage, she may never forgive herself. So lie, and lie well. Don't put that on her, no matter what you do.