I amsorry. I can relate to your pain. My AH had a few relapses before I knew what my boundaries were. Actually they seemed to come out of nowhere until I said them. Up to that moment I was not sure how much I could take. Everyone has to figure out what they are and when to set them for themselves.
As for the cookies. Did he say why he was hiding them? I learned that many alcoholics in recovery have a big sweet tooth. It helps with the cravings. You should have seen the desserts at AH's rehab center! When he came home he would eat a carton of ice cream by himself in 3 days! When he stopped eatting it I knew each time he was heading for a relapse.