Am I being a jerk for breaking up with my gf?

ok, so we are seniors in hs with different home rooms. on wednesday morning i guess my gf was laughing so hard at something that she farted and it was pretty loud. when i saw her in the hall she was so upset she wouldn't even talk. i had to find out what was wrong from her best friend. we go to a small school so everyone knew by lunch. so the guys started coming up to me teasing about how my gf farted in cl and I told them we broke up. so word gets back to my gf that I said we broke up. now she is really upset. I dont like to see her upset, but I dont want to be known as the guy with the farting gf. any advice?