The world is not just black and white. Right and wrong.
We are human and errors of judgments and morals happen every minute of every day.
Your cousin had his role in the infidelity - like it or not. Not one single person on this site is blameless for their situation. No one sets out to turn the worlds of our families and friends upside down for pleasure.
Something triggers the chain of events and even if your cousin thought he was the best H in the world - he was not meeting his W needs. To have an affair is definitely not the answer but to me it was a final cry for help.
You can stand up for yourself, by digging to see what went wrong , correcting , improving yourself and not accepting anything but the best in your future relationship. Your cousins first priority is to his children and to minimize damage and see what can be salvaged. An A does not have to mean the end of a marriage. It can mean the beginning of a better more healthier one.
