Well, suffice to say that I do not condone, nor have I ever condoned, hitting girls.
I was fourteen as well, maybe fifteen, and walking home on my own (as per usual). A rather unpleasant girl from my History class was walking with her friend a few feet behind me. After a few minutes of whispering, a ball of paper hits me in the back of the head. Then another. I try to stay calm, and start to walk more quickly. They keep up, and start throwing small stones. Those hurt.
I turn around, and ask them as politely as I can manage to leave me alone. They smirk, I sigh; I turn around to keep walking while the girl jams her foot around my ankle to try to trip me up. I keep my balance, just.
I'd done my best to leave fighting behind me at primary school (and I did my share back then), but after a few minutes of repeated tripping and the occasional smack to the back of the head, and every pacifist/cowardly option exhausted, I turned around to shove her away.
I'm not quite sure when in the following two seconds I decided to punch her in the face instead. It didn't feel like a conscious decision, but then spite is a powerful thing.
I hit her, she stumbled back, her friend went quiet. She looked puzzled, and then burst into tears.
Two blokes on the other side of the street turned around and started making their way across the street whilst calling me things I hadn't even heard before. Feeling it was safe to assume that they'd taken her side, I went for the sensible option and ran like fuck.