There are two versions of yourself: Your version, and everybody else's version. Each decision you make affects one or both of these versions. You have to find a balance between what YOU want and what OTHERS want. You might wanna wear pajama pants to school tomorrow, but you probably wouldn't do that for a job interview, right?
Also, if he is your best friend, he'll drop it in favor of your friendship. I know that's kinda cliche, but its so true. Just tell him "Dude, lets just agree to disagree. I wanna be friends." If he doesn't like that, then he doesn't like you. In my experience, people who don't treat their friends well usually only have them for the ego/social-status boost that comes from having someone who just lets them do as they please.
On the other hand though, it really sucks to lose someone you liked. Sometimes you gotta just let them win, and hope they were just being a dick temporarily. If its as "dumb" and "stupid" as you say, I'm sure you would have no problem letting him have this one.
Its 2AM and this post makes sense.