You have come to a great place for all kinds of help. The sharing of pain lessons it. The fact that you are here says to me that there is a faint glimmer of hope that you wish for your marriage to survive. Is this true, or was your affair an "Exit Affair." How hard are you willing to work to make this marriage survive? An affair doesn't mean a marriage is over and many marriages survive an affair. In fact, some say that their marriage became stronger after an affair.
If you discovered that your husband cheated on you, would you be able to forgive him and save the marriage? Do you love this man so much that you will do what it takes to save you marriage. Does he love you as much and is he willing to work as well?
You will have to tell him about your affair. Not yet, but he will have to know at some time. Are you ready to work through that? There will need to be a clean slate before there can be any "true" healing.
I am sorry for your pain and that you find yourself in such a sad place. Keep your chin up. It isn't forever and you will get through it. When you are going through hell, just keep going!