it appears to me that there's a few things you could do...

THE EXTREME
1. stab the bitch to death
2. go on a postal rampage and shoot all of your co-workers
3. skin her dog
4. pay me to do unspeakable evil towards her

THE LESS EXTREME, YET STILL SINISTER
1. pour sugar in her gas tank
2. let air out of her tires
3. toilet paper her house
4. fuck with her back, try and start a fight, but wait for her to throw the first punch

BUT WHAT YOU SHOULD DO IS...
well, first off....i mean, are you gonna get in trouble? like, lose your job or sumtin'? if not....then FUCK IT.....just say fuck it and smile about your day.....

the best thing you can do is just avoid her....let her go about bein' her bitchy self, and hope others will see she is a fuck.....i wouldn't bother with "telling on her," but just forget about it, go home, and take a nice hot bath....let her be a bitch, and just stay away from her.....and if she doesn't want to be a part of the group, fuck it, let her leave....what should you care? a person like that doesn't need to be in foster care anyway.....and um, just because i'm all evil like, those fuckin' eskimo's know how to hunt whales, what does it matter if losing her means one kid remains on the street? who cares.....some of the greatest minds and artists live on the street.....

but seriously, don't let her bother you.....when things get my panties (i'm a guy) in a twist, i just take a deep breath and say fuck it......tomorrow is tomorrow....hopefully the world will end

and the plural of knife is knives......yay! i have a degree in english, and it shows!