This is one of those things that is so horribly not funny that it completely is. Or maybe you just need the right wrong mindset.
Myself? This was hilarious. Sure, you feel bad for the little girl. Who would want to get slapped in the face so hard? I sure wouldn't. The thing that did it to me, though, wasn't so much the slap as the result. The little girl didn't stumble away and fall, THAT might have made me feel bad. No, she practically FLIPPED backwards when she got hit.
Am I going to hell? No, cause I'm already there... XD