Is there a line? At what point is it crossed?

I was reading a page on Facebook that is supposed to be helpful and at the same time a vent page. It's about bad drivers. Most people post about vehicles getting stolen, or warning others of a driver being reckless and to take caution when encountering these specific drivers. But lately as I've noticed the page is dancing close to cyber bullying people. They go out of their way to screen shot peoples arguments and photos before the origanal post gets removed because They're harassing them so much. Then when the said person removes their post or photo they plaster screen shots of the origanal poster's Facebook profile all over again and continue to call them pussys for taking it down. Then that person who's profile is posted gets harassed all over again through messenger. The people who are doing this to others are full grown adults with families which baffles me. My question here is, when is the line drawn the line between speaking your opinion and cyber bullying?