What should I do about a girl spreading lies about me at school?

In a situation like this it is best to prove yourself as the bigger, better, and more mature person. She's 14, the people that listen to her are probably around 14 as well right? The age difference right there is enough for a person of 17 to look at her and wonder why in the world she is being that immature of a person. Tell her you think she's being immature and when she cocks an attitude and tries to start more things she's just proving it that she's being immature. You can continue to point that out. And surround yourself with friends that will listen to what you have to say and not take her side. That's an important thing too. Hopefully she'll grow up with time and at 14 things like this aren't important in a couple of months. It should die down, but you shouldn't just "sit by and deal with it." Make yourself feel happy and in the end separate yourself from her. The negative energy is just not needed.

retaliate, outsmart her, win!even more important, you have to stand up for yourself. Don't let her bully you -- you're a grown woman she's got years to go. Dont take her pre-teen crap!

i went through this kind of situation at my school with a few girls spreading rumors, i went to my school chappy and he told me not to let these girls push my buttons, don't respond to there insult and get grumpy, its just what they want, your reaction, so just know that you have good friends around you and that those words mean nothing, it worked well with me and the girl left me alone, maybe this will work for you too