When I was 8 years old I had witnessed my dad abuse mom all my life. One night they argued and he slapped her. She fell and hit her head on a coffee table, knocking her unconcious. I ran to my parent's room and grabbed my dad's .38 revolver. Ran back to the living room, stuck it to the back of his head as he kneeled over her(I assume checking her out) and cocked it telling him to back away or die.

Idk if it was his fear of dying(because I was DAMN serious! That was Mommy!) or the simple fact that his actions led to his 8 year old son putting a gun to his head, but he left the house for the night and has never laid a hand on her since.

My father and I get along now, but I would say that was my defining moment. The shittiest part is I missed out on all the "kid stuff" from 8 years old on. I was always ready to enforce my promise.

That being said, I think I may have spoiled my son some by making up for my lost childhood.