13. The Thin Line Between Chuck and Nate

Gossip Girl reports that Serena van der Woodsen was seen buying pregnancy tests. Of course, on the Upper East Side, the truth is often even juicier and more scandalous than the gossip. Nate finds out about Blair and Chuck's affair. And when everyone else finds out what happened Blair's life comes crashing down. Meanwhile, Dan struggles to tell Serena those three special words.