WTF Moment - Am I Cheating?

This entry helps to show why I am past the point of sanity.  I really professional help to deal with the stuff I encounter daily.  Last night after I returned from my dinner with friends, my wife decided she wanted to talk to me.  She came and sat in the room and wrapped herself in a blanket.  She proceeded to strike up a conversation about various topics.  While talking she asked me, "are you cheating?"  WTF?! Who does that?  What was she expecting for an answer??  Now don't get me wrong. I have cheated in the past.  I thought we had gotten past all that but apparently she refuses to let go.  I try to make sure I mention the names of females I work with as well as their life statuses (married, dating, kids) to ease my wife's mind.  I am starting to think there is nothing I can do to help calm her self inflicted paranoia.