No matter what she offers, say "Thank you for being honest with me (or, "I wish I could believe that," depending on whether or not you think she IS being honest with you); I will need to think about this. I'll be back in touch. I hate to cut you off, but I have to go (insert GAL activity HERE). I'll get lunch."
Then leave.
btw, if you KNOW what she says to you is an OUTRIGHT LIE -- CALL her on it. "We both know you're lying to me right now. Please stop it; it's incredibly disrespectful to me, to our marriage and to our family."
