Why would my husban lie about his entire past?

My husban is given me the creepin willies. He made up his entire past. Up until the other day I thought he grew up severly mentally retarded until age 14 when he fell into a ravine and damaged his skull. The physical injuries he sustained from that fall supposedly jarred his brain into a more normal functioning state, rendering him not only no longer retarded but quite intelligent. I believed that story for the last 7 years. I told friends and family about it. We told our children about it. I was asking for his medical history because he is having a skin reduction around his bulb and he left me to fill out the forms. When he was talking to teh doctor I brought up his past and the doctor was very congfused. My husban just said, 'she's making that up. it hasn't happened'. I was so embared! I havent shown my face back to his doctor since! Why would he make this up!? Why would he treat me bad to the bone!?