I have a strange addiction and am wondering if it has a name.?

My wife's parents hate me and they don't even try to hide the way they feel about me. They put me down constantly telling me that she could have done "so much better", and no matter what I do, in their eyes it's wrong. At our wedding her father made a toast which included "We respect our daughters choice and even though Mike is not a handsome guy and has a terrible job, we will accept him into our family as if he is our own."....What makes my situation frustrating is that my wife becomes absolutely enraged if I try to defend myself. I am not allowed to talk back to her parents no matter what they say. I get them back in other ways. A couple of months ago I snuck home from work in the middle of the afternoon when I knew they were over and I poured a bag of sugar in their vehicle's radiator and ruined the engine. I was ecstatic. It was like the biggest high you can imagine- A complete and utter thrill. Ever since that day I have taken to other sneaky ways to get even with them. Every Friday they come over for dinner and I am doing stuff to their food. I know it sounds bad, bu