Your post struck a cord with me so I thought I would respond. In my case there was the issue of not being able to say no. I too had an affair and all the same feelings came up as when I was abused. I can tell you that the pain does get so bad that we do things that we may not normally do even if it hurts those around us. I have posted my story on another web site. http://spiritualsurvivor.org/
This may give you a little insight as to what is going on with your husband. Please keep in mind however that each man is different in how abuse affects him. My story is not his story, but it may help you understand a little bit about what goes on in our heads and hearts. Good luck.