I could not agree more with WellWobbly. I suspected my ex of cheating in our first year, and when I was pregnant in our second year, he always denied it. I even used to have nightmares of him walking off with another woman and just looking straight through me. I used to wake up and tell him about my dreams, he used to say I was being silly. Now 20 years later, 2 years after our seperation and consequent divorce (I left him as he treated me with no respect whatsover), I finally got the truth, yes, he was cheating on me during my pregnancy, and then went on to sleep with an estimated 42 prostitutes!
He didn't have the guts to tell me when we were getting a divorce, he made me do all the work, only so that he could say 'I'ts what you wanted'. When I got angry once I had finally found out, his response was 'It happens to other women all the time'. I didn't have the 'right' to be angry, because it was all in the past, and we were already divorced. He still doesn't acknowledge that he did wrong by me. The worst thing I did was strike up an emotional connection with an ex boyfriend, and that gave me the strength to leave. I was faithful to him until the day the divorce papers came through.
For a man to be physically intimate with another woman, and then to come home and expect you to do his washing and cook his dinner.... I did it unknowingly for years, but it always felt wrong, and he was very good at belittleling my feelings. He used 'gas lighting' to draw me off track, kept me on my toes, I never knew what I was doing right or wrong, it could be either.
I am really sorry that this has happened to you. I am now, alone, but so much more at peace, I do not wake up rigid with anxiety, grinding my teeth. I no longer walk on eggshells. The saddest part is that my DD knew and was unable to tell me, and she carried his burden. She no longer talks to him, and of course I am being blamed for that too. Do yourself a favour, go look at a website called 'lovefraud'. See if that helps any, it did me.
Good luck debtherat with whatever you choose to do, it is an unenviable position to be in, but make sure you direct your anger and hurt at the person who has done this damage, him. Once you start standing up for yourself, and look him straight in the eye, and know that you are right, you will see what a coward he is. And as a side issue, I taped absolutely all of my conversations with him, it's good to have proof. Just in case.