+1 with whiteowl and Veronica. I work with almost all men (engineering company). They are always needling one another and tweaking one another. I guess they haven't stopped from their middle school years. I say he was messing with you completely and took it bit too far. I guess he was hoping you would stop. Hitting him like that probably taught him a valuable lesson, not to mess with cyclists or cars.

Yup you don't want the brake/brifter lever bar cranked down too hard on the handle bar. It's always better if they can twist away in a crash in stead of breaking the lever. I can't imagine your handle bar was tweaked from a slow speed fall. Even at high speed crash I rarely see a twisted handlebar.

don't be too hard on yourself. You're not seriously hurt, nor the boy.