"I just try to be really, really honest with people when I think that they suck."
Yup, Santana Lopez from Glee. She sings, she dances, she thinks she's tough shit and gives no fucks. She sluts about without shame and speaks her mind when people do things she thinks are stupid... And she goes above and beyond to protect her friends, even if they don't realize it or understand her unorthodox methods. Generally Xenedra is not actually as bitchy as Santana unless she's angry, but the high emotional walls and attitude are definitely there.
Alternatively! Denna from the Kingkiller Chronicles. Many names, unclear past, uses her charm to her advantage. Once again musical, confident and insists on hiding her sensitive side.
http://kkc.wikia.com/wiki/Denna