Father kills his 15 year old son execution style

As I patiently laid in bed waiting for my toddler to fall asleep, I was watching the news and was shocked with the information I learned.

What has this world come to?

Jamar Pinkney Sr killed his 15 year old son, Jamar Pinkney Jr because he was told by his son he had raped his 3 year old sister. He beat his son badly and rushed the toddler to the hospital to see if there was penetration. Later that day he received a call from the hospital and was notified that in fact there had been no penetration. After the boy received several beatings he then told his parents he had only rubbed himself against the little girl. Jamar Sr was full of rage and ordered the Jr to undress and step outside. Jamar Sr led Jamar Jr to an empty lot next to his house and told his 15 year old son to knee down naked. He then shot him in the face execution style.

I ask myself how I would react if I was in that situation. I couldn't imagine anything happening to my little girl, there's no explaining how I would react. Give me your feedback, what would you do?