I hit a young child and his father. I don't feel guilty...

Hello..
First let me introduce myself. I'm Varni, a filmmaker. I have 2 very young sisters.
We often do crunch overtime in my business but there are times when we don't have anything to do, then we don't even go to the office and stay home, allowed by my company.
Today was such a day and I decided, I should take my sisters to the park. the older daughter refused, she would stay with mom and visit a neighbor, but my four-year-old little sister was joyful.
So we prepared and hit the park. It was crowded but still nice, people were kind, the toys in the park were in mint condition, the grass was green and a light wind was bringing us the smells of flowers.
My sister got tired after some time and begged me for snacks. So we visited a nearby pastry shop and bought a good amount of assorted cookies, also lemonade for her and me.
We got back to the bark, found a nearby bench with only a woman was sitting and settled. Then he came..
A young sphere, about 11-12 years old, walked to us and stood right in front of us, glaring. I told my sister to offer the "big brother" cookies. He got his handful. Everything was still normal. But he inhaled his handful and then reached for more.
Then all hell broke loose. My sister moved the box away, she wouldn't share more. The kid, relentless, grasped my sister's arm. My sister winced.
My sister... winced. I can't say I'm fond of unruly kids anyway, but noone hurts my sister. I stood up, said "No!" firmly and removed his hand. He stopped for a moment, tried to reach and pulled back the first thing he could grasp. My sisters's hair. My sister screamed in pain.
I confess, I was a little shocked. I could have been calmer. But such behaviour isn't normal for kids in my neighbourhood and I was surprised. I acted without thinking. I backhanded the kid. I was sane enough to hold back but the impact was enough to make him fall to the ground and start crying.
Then the earth started to rumble and shake. I looked up the sky, thinking if I pissed off the God by hitting a child. No, not really.. His father was coming. "Like father, like son"... Just like the kid, the father had also embraced the Sun Goddess and assumed the spherical shape of the sun religiously. I'll simply call him "Sun" for short...
I was already fuming but there was no target for my rage. So the father came and asked "What's happening?"
Me: This is your kid?
Sun: Yes, did you..
Me: Your son pulled my sisters's hair. Why aren't you taking care of your child?!
Sun: Did you hit my kid?
Me: Yes, if you aren't around to make him behave, I do as I see fit to make him.
Sun: ......
Me: My sister shared her cookies with your son, then he tried to grab more and grasped her arm, then he pulled my sisters's hair.
Sun: So are those cookies so expensive?
Me: That's not the point.
Sun: So you hit my son for cookies? I'll _uck your cookies.
Then he tried to slap the cookie box out of my crying sisters's hands. I'm not the person with greatest reflexes, but I managed to hold his arm and pull him back. Then he tried to push me aside and slap it down again... We literally started wrestling, him trying to push me into my sitting sister.
I pushed him away one last time, then when he raised his arms to push me, I punched him. Hard.. In the guts.
I was readying my second fist but one was enough. He toppled on his knees holding his belly. I remained still with my fist raised, then calmed myself down. I leaned towards him and spat out at him to have sexual intercourse with himself while removing his presence from my surroundings through gritted teeth. Thankfully, he did so and things didn't escalate.
Currently it's late night where I am. I was reviewing what happened in my head. Surprisingly, I don't feel guilty at all.. Civil courtesy must have its limits. I can't afford harm coming to my daughter. I confess, I feel even a little proud, hence this post. I do sincerely hope he also reviews what happened and tries not to attack toddlers' cookies next time.