The Narcissist is always happiest when he/she can keep you upset and surrounded by chaos. After you leave, the best thing you can do is live your life happily. They envy that you can actually move forward while they can't without a new supply.
Most of us experience stress of some degree in our day to day lives and a big part of managing stress is exercise and nutrition. Digesting processed and sugary foods on a regular basis just loads extra stress onto our bodies so try to think about nourishing your body and giving it the tools to manage stress.