What your husband has done is not only very hurtful but also very wrong -- not only in your eyes, but in the eyes of God. The Bible condemns adultery, and Jesus' words are clear concerning the sacredness of our marriage vows: "Therefore what God has joined together, let man not separate" (Mark 10:9).
This is why I hope you will do everything you can to restore your marriage. It may not be possible, I know -- but I urge you to try. After all, at one time you and your husband were in love, and you were happy. What went wrong? Did it start with bickering over something you should have worked together to solve? Did you lose the ability to communicate, and end up arguing all the time? Did you lose the ability to forgive, or forget to be thankful for each other?
Whatever the reasons, my prayer is that you will turn your marriage -- and your entire lives -- over to Jesus Christ. God knows all about your problems, but He still loves you and wants to help you. He can even give you a new love for each other, as you make Him the center of your lives.
Even if your husband refuses to change his ways and it becomes necessary for you to go your separate ways, don't let bitterness, anger, or feelings of failure overcome you. Instead, find your joy in Christ and His people.