Hi bluesky. You are going through a lot. Both of you could benefit from some counseling.
If you feel that people at work know about it and are laughing or talking about it I would put the blame exactly where it belongs, on your husband. I would also tell that husband to quit humiliating you and either go to counseling with you or get out. Why should you have to suffer from his affair?
He sounds as if he has some problems. It is not fair to make you sufffer.
The affair may be an emotional affair or one of those on lines deals but is an affair never the less.
I know it has to be really bad for you because someone you love is letting you down. You need to do some thinking as to how long you you can stand to put up with this.
Also if people are joking about it at work please think about getting a different job. Let us know what happens. Take care. MaryAnne