The thing that annoys me the most about this is the whole "he's not being a jerk, he was just hurt before" crap. A bad past may be the reason why you have the impulse to do something but it does not excuse you from acting on that impulse. I've been yelled at by customers at work before but that wouldn't excuse me running them over with a car even if it would explain the thought coming into my mind.
The thing that annoys me the most about this is the whole "he's not being a jerk, he was just hurt before" crap. A bad past may be the reason why you have the impulse to do something but it does not excuse you from acting on that impulse. I've been yelled at by customers at work before but that wouldn't excuse me running them over with a car even if it would explain the thought coming into my mind.