JJ, when I first started teaching I lost some serious sleep over being an authority figure, having a hatred of authority myself. My second year (first year as a full-timer) I actually had a kid call me a "fucking cocksucker" IN CLASS and couldn't figure out what to do (I told the department head, who had him barred, and I don't know what happened to the steroidal bastard but I hope he flunked out. My standing in the class never really recovered from that).
What I learned, eventually, is that it's school. It's not life and death (school shootings aside - I actually have a kid this semester who worries me a little). Those girls might have cried, but they'll get over it. You're not putting single parents on the street, or injuring these kids or costing them lots of money or putting them in jail - you're the poor fellow who's stuck with the job of telling them they can't live in a classroom. The other thing that I learned is that an asshole doesn't stop being an asshole just because he's a student and I'm his teacher - I've learned not to take anything personally, but I also don't take any crap that I wouldn't take in any other aspect of life. By the same token, I don't treat the students any differently than I would treat anyone else - i.e., I try to be generally decent. I still don't like failing students, but everyone seems to get that it's not personal, it's university requirements and so on. As in most things, now that I don't care about being liked, the kids seem to like me a lot more.