I can't even address you by your screen name, because you are NOT pitiful. I am so so so glad Sandi wrote what she wrote to you.
I had a bad feeling from what you first wrote, and I really see why now. You said he could be cruel before your indiscretion. And I do not see this as an A. Maybe it would have become one, maybe not, but you had lack of better judgment, but you are not an adulterer.
Before this happened, he had a cruel streak as you described it. My ex had one of those too. I'm afraid he sees this indiscretion as now having an excuse to be cruel. And now you see it as an excuse for being cruel too. There is no excuse for being cruel, quite honestly. And that is what he is being to you.
Perhaps you need to start drawing some boundaries. letting him know "if you continue to keep treating me as less than human, I will have to move out until you decide you want to repair this marriage together with me. I will no longer tolerate your belittling me. I am sorry I have hurt you, and I would like to earn back your trust and love together with you, but I will not be abused."
Right now it he wants you to loathe yourself. And no one can having a healthy marriage from a place of loathing. And you shouldn't. Yous ay you were best friends prior to this, but best friends aren't cruel.
My ex spoke in a cruel manner to me. And it messed me up big time. Took a lot of time to repair that damage. Best friends don't do that.
please take care of yourself. Don't let him treat you the way he does because you think you deserve it. Your marriage will not be a long lasting one that way. And you will lose yourself.