Now I've dealt/regularly deal with people like this all my life. Unfortunately, in my experience, few of them are capable of/are aware of/are willing to try to change this behavior. Whether they are born this way (predisposed to just negative yuck) or whether it is a learned behavior (abusive past, negative yuck at home or just extreme bad luck), we really have no way of knowing. And we really can't do a whole lot for them.
What we can do, is chose not to get sucked in to their negativity. We can stand up to their verbal abuse, constant criticism & atrocious behavior, both by telling & showing them that there is a better way to act. A nicer, kinder way to treat people.
I've seen a lot of my friends, particularly on Facebook, post comments where they talk about how someone has been bashing them both online & in person. I've been there, I know the pain & hurt some of those comments can cause & I'll admit, I don't always react in the best way.
Certain people's words or actions can cut deeper & (at least in me) cause more of a primal reaction; I tend to verbally lash out at these people's comments with my own anger & hurt, which can & has resulted in me doing just as much damage as the other person. This it a natural & sometimes even necessary way to handle some conflicts, but that doesn't mean it's healthy.
For the most part, I am usually pretty good about breathing deeply & calmly , rationally handling the situation. I have never liked conflict, but I haven't always tried to avoid it either. I just make a concentrated effort to not only take the moral high road, knowing that everyone has faults & that "perfect" is really just a notion, an idea of what we would like to be, more like a flight of fancy than an achievable goal.
***Sorry, just realized the train stopped for a moose on the tracks & the engineer wandered off looking for faeries. No worries, I don't have a pilot's license but I'm sure I can get this train back to Hogwarts in no time.***
Anyway, if you find yourself on the receiving end of this type of crappy treatment, do me a favor. Take a deep breath, smile & remember that whatever was said, was just that person's opinion & more likely than not (as with most of these situations) reflects more of what that assbutt feels about themselves that what they truly think of you.
Also, I love you, just as you are. Even if you don't like Spam (the food not the junk mail), bubbles or hugs. Hang in there & always know that there is someone out there, who thinks that you are the best thing to ever happen to this world. Even if you're not aware of them.
Aloha hugs m'luvs,