I'm going to bitch at my roommate
Why would you yell at your roommate?
I hate the way he talks to me like I'm some kind of preschool kid
Being treated like a lil kid is one of the worst things as an adult, I can relate to that completely. Bitching back at him will just give him the satisfaction he wants. What you should do is ignore him, because then with no reaction from you he will be bored and pick on you less.
I have no idea how I lived without this advice.
I'm really glad you're gonna take my advice!