Huge sympathy - but I'm putting a plea in for no night off the diet. Why should you let this woman put you off your stride? Don't let her have that too - if you're seriously trying to lose weight, don't give her the satisfaction of turning you to the dairy milk!
Ex-dieter - speaking from experience. If you can crack turning to food in horrendous times like this, you can do anything. Go for it, and again, huge sympathy.