Huge Spoilers ahead for Transformers One

Hello Autobots,

I've got a question for the scene where D-16 shoots Orion Pax accidentally and catches him before he falls into the abyss. I don't understand why he first saves him and then says something along the lines: "I am tired of saving you" and let him fall.

Where was the Point of no return? D-16 seemed shocked that he shot his friend, but then let him die? I don't get it.

Everything before made sense. D-16 whole world was shattered. He wanted Sentinel Prime to suffer for what he did.

Did D-16 turn powerhungry? Was his revenge not satisfied yet? Did he wanted to destroy everything that was left from the old world? I really don't get it.

Maybe someone can enlighten me.