I know it hurts like a sucker punch to the stomack each day, but each day, week, will get better and you'll be one step closer to healing. If you are not going to counceling do it NOW, my H and I have done progress after our C session Monday (I discovered op back with him again on friday)
And the book "healing the hurt in your marriage" was a life saver to me too, you need to fill your mind with positive reads and not let your mind wallow in negative thoughts, in rehashing the events of the A. You CAN train your mind to lead you away from hurtful and unproductive thought to a place where you can heal.
What's past is past. Your husband had feelings for another woman, and he was emotionally messed up (impaired), so his feelings were messed up too. Our feelings often follow our actions (because we have to begin to think differently in order to act differently). Today is what matters, and the future, not that brief moment in time when your husband screwed up royally (which did not make you a lesser person of a lesser value - it made him lesser). Today your husband has intense feelings for you and he is learning and doing the actions necessary to keep growing in his intense feelings for you.
You can leave if you want, and perhaps find another man who you've shared nothing with so far, who is not the father of your children and who also once had intense feelings for another woman (or has something wrong with him at this age), and what will you gain?
Why not let go of the past? So it's got an ugly black spot on it. I don't think there is a person out there who doesn't have an ugly black spot of some sort on their past. How well you handle rejection is part of what makes you a beautiful woman (or man) to be admired.
This is your life. Take what you want. Do you love your husband/wife? Does he/she have intense feelings for you today? Has he/she learned from his/her mistake and changed his/her behavior to ensure he/she always has intense feelings for you exclusively from this day forward? Then don't let your past rob you of what belongs to you today. As in the Robin Williams movie, Dead Poets Society, "Carpe Diem!" Seize the day!
Be not afraid...I will repay you for the years the locusts have eaten Joel2
30something 2kids survivor of S, MLC, A, D I have peace in my heart, at last.