The worst time for me, of course, was when I first learned that my wife (now ex-wife) was fucking with other men! I had been completely faithful to her and was sure she was, too, but she threw it up to me during a heated argument that she was "putting out" for several other guys.
It literally blew my world apart! It took a long time to ever come back to reality and begin to find ways to cope with the reality of what had happened. I remember moaning to myself "They fucked my wife! They fucked my wife!" over and over. At that time in life, the belief that I had exclusive rights to her pussy was very important to me, and when that fantasy was shattered, it took a long time before I could ever feel "normal" again.