Oh I know personally. Right before I started dating my wife, she had been dating an officer who turned out to be bad. He was ultimately fired but she suffered before he was.
My lay opinion is the concentration of "Type-A" personalities, exposure to all manner of human cruelty and the stress of managing unknown contacts on a daily basis, all contribute to the much higher percentage versus the regular public.
I have no doubt all of that may be true, but it doesn't excuse the behavior.
I have no problem with the split second decisions officers have to make when they find themselves in certain situations and would NEVER presume to second guess them. However, there is no denying that a statistically high number of officers have poor coping mechanisms for what they deal with on a day-to-day basis and the general public and those officer's families are the ones who suffer because of that.