Badness

Y'know how being around some people makes you feel tired, sick, and drained afterward? I had such an experience last Tuesday, and am just now getting to where my spirits can be lifted again. I've debated whether or not I should blog about it, but what the heck. I doubt the person-in-question will ever be reading this anyway.
It happened at ABC group, after we'd eaten. We were sitting around outside, talking amongst ourselves with the usual humorous irreverence. One person, who isn't usually there with us, made a point of talking about how he's done various kinds of drugs. Pretty much everything goes, as long as he doesn't have to inject it. (THAT creeps him out, but any other form of ingestion is just fine). It was bizarre to hear him speak so casually about it, as if he was proud of it and thought it made him knowledgable and cool. I just kept getting this feeling of uneasiness, which turned to horror after he told one particular story:
He used to work on a pig farm. There were mice who nested in the rafters of the barn. Sometimes the newborn baby mice would fall out of their nest and hit the barn floor. This guy liked picking them up, still live and wiggling, and holding them in front of the pigs' mouths. The pig would then eat the live baby mouse, scarfing it right up as eagerly as a dog eats table scraps.
This guy thought that was hilarious fun.
He made a point of describing the helpless little mice-- still blind (too young for their eyes to be open yet), smooth, pink, and utterly helpless. He mimicked their wiggly movements by closing his eyes and moving his forearms around. And he loved the thought of them being eaten alive by the pigs.
Ok... mice aren't exactly my favorite creatures, and neither are pigs. But I think what he did was horrific. And the fact that he enjoyed it so much makes it truly evil.
It takes a LOT to offend me, and I'm usually not affected this way by people. But by the time I drove home, I felt shocked and ill. Drained. This person's energy felt really nasty to me.

Have any of you had a similar experience? How did you "shield" yourself from future recurrences?