stop scaring him.
He sounds like a nice kid, just be who you are, a nice guy, and they'll understand you're just a nice kid who likes to smoke but the law is the law and you got in trouble, but jail time shouldn't be necessary. Probably a fine or some bullshit is all you'll get and a 'don't get caught again' bullshit from the judge.

Assuming you're black, let's hope they don't judge you and shit, so I hope you don't run into that kinda thing...
good luck.