> My boss calls me stupid, incompetent, r*tarded, and "like you have part of your brain missing". He grills me on literally everything I do, like why I'm getting up from my desk or why I'm eating what I brought for lunch.

yeah... that's not normal even a little bit. look for a new job. i have a hard time that any company that allows that kind of behavior is any better in any other department so get out ASAP!