Hi Blake, I don't have a lot to add as I haven't been through what you are going through. But I've read your posts with compassion and have been a silent supporter. I thought I should let you know that you probably have many silent supporters. I too hope you will cut your losses and move on to a happier relationship, once you have worked on that codependent tendency.
Perhaps I feel invested in your situation because my mom was there for ten years when I was a child. I lived in chaos and fear all those years. Mom would tell me we were leaving and pack our bags, I'd think hope had come at last. But he always managed to say something, threaten something to make her stay. It got worse and worse. If you ever want to have kids some day, think of them and learn how to draw the line now so that you are not learning with their impressionable hearts at stake. You can do it!