Yet, the hardest thing to process is that H had an EA with OW. H gave the OW the exact thing that I desperately needed. How was H capable of meeting the OW emotional needs when he was never capable or willing to meet mine? Does he just love her more? Does she ask in a way that I had not previously asked?
Remember back when you were dating H, the fun and excitement of it? How fascinated you both were with every single thing that came out of each other's mouths? How you couldn't wait to see each other again? How it seemed like you were high on a drug, euphoric, and you never wanted the feeling to end? That's limerence, otherwise known as "puppy love". It makes you see nothing but good things in the person you're with and you ignore all the bad stuff because it just doesn't seem to matter, because you're in luuuuuuuv! THAT is what H is getting from OW. You can't give that to him, because that ship sailed long ago from your own M and gave way to a more permanent, lasting and real form of love. Limerence is driven by a release of natural chemicals into the body- serotonin, dopamine, etc. It is enhanced when one or both of the parties is married, because there's excitement over the secrecy as well. But it is unsustainable. In time the chemicals are no longer released and the people start to see the relationship more realistically. Things that didn't matter before are suddenly obstacles. Like before she thought it was great that he makes those cute little sounds when he eats soup. Now she's repulsed that he makes those awful slurping noises while eating soup. How long it takes for it to wear off is tough to say, I've heard from 3 months to a year. But the vast majority of A's end when it wears off.
Everything you described about his R with OW positively screams limerence. OW clearly has some major issues, and right now your H is ignoring them because of limerence.
But there's nothing you can do about it, that has to run its course. In the meantime you've got to focus on you and your boys.