Second paragraph:
"Sources have identified the boyfriend as former right-winger Lew Rockwell of the Ludwig Von Mises think tank located in Alabama, WHO IS HIMSELF MARRIED." (emphasis mine)
Thanks, and eeeeeeew.
If you're married and stepping out, the person with whom you're stepping out is properly referred to as a side thing.
If you pay for your side thing's living expenses, you can call the side thing your mistress. (Or your boy toy, if you're femalish.)
But no, when you're married you don't get girlfriends or boyfriends.