She needs Your Advice, Her Husband Has Been Sleeping With Her Mother And He Thinks She's Sweeter Than Her

My mother is an attractive and interesting woman who dresses fashionably. Recently, I found out that my 39-year-old husband has been having s’e’x with her when he attends conferences at the resort near where she lives. When he told me, I was bothered by the fact that it didn’t bother me.

He’s a wonderful man—father to our two children and a good provider—and he’s always taken care of me emotionally, se’xually, and financially. I know I should be upset; I know I should feel betrayed on so many levels. But I just don’t. He says he enjoys the relationship with her but will stop if it’s what I want. Honestly, if my mother and husband are happy in their affair, I just can’t seem to find the energy to be angry or jealous. So my question is: Is this normal? Should I be upset?