SadSister,
So sorry you are here, but glad that you found this site. It is filled with an amazing group of men and women who have been and are going through exactly the same thing you are.
Be gentle with yourself. As Trusted Her pointed out, the A may have occurred 13 years ago, but to you, it just happened. Try to eat, drink water and rest when you can. You are experiencing one of the most horrific traumas one can go through. Your emotional state will run the gamut, from sadness to hopeless to anger. Wash, rinse and repeat.
I'm two years out from finding out about my Husband's affair and I can tell you (as can others) that it's one step forward, two steps back.
The onus is on your husband now. If he is remorseful, he must show you he's willing to do anything to save this marriage if you decide you want it to be saved. He must be open and honest and willing to answer any questions you have. He must be consistent. Don't make any decisions right now. His actions must match his words. You can't "get over it" just as he can't erase what he did.
I can tell you from personal experience that I felt and still feel at times that I'm not sure I can stay with a man who so carelessly threw 20 years of our shared history away and that is with a remorseful husband. I was always the one who said infidelity was a deal breaker. Then it happened to me. It's not so black and white when you have built a life with someone who then sets off an atomic bomb in your marriage.
Take it one day at a time. Sometimes one minute at a time if that's all you can muster. I'm glad that you set up counseling for yourself. I did after discovery and also insisted that my husband go to individual counseling as well. I would also suggest marriage counseling, but only when you're ready.
Check out the Healing Library, there's a lot of great reading there.
Others will be along shortly, many of which have been successfully reconciled, but I wanted to let you know you've been heard. Welcome to the best club nobody ever wanted to join.
Peace, support and love to you...
BEM817