Gossip Girl, Season 2

Serena:
Everything you've done, spreading rumors about who I've had sex with, what alley I puked in or telling Dean Barrowby that I killed Pete Fairman, I forgave everything all because I thought one day you'd grow up. But putting up a Gossip Girl blast about Yale and the press release ...

Blair:
Serena, I didn't put out the blast.

Serena:
At least have the dignity not to lie to my face.

Blair:
But I'm not lying.

Serena:
Only two people knew about it, you and Dan. And Dan would never do something like that. I always want to believe the best in you, Blair, but the bottom line is, betrayal's in your nature.