What episode was it when serena and nate had this conversation(GOSSIP GIRL)?

EXT. BY FIFTH AVENUE – MORNING

Nate chases after Serena. She runs away from him.

NATE
Serena. Hey. Did you get my text?

SERENA
I lost my Sidekick last night. You have to
stop calling me. Blair and I had a great talk.
Things are finally in a really good place –

NATE
(blurts it out.)
Blair knows. I told her.

SERENA
Why would you do that?

NATE
I was trying to do the right thing. Since that
night – I haven’t stopped thinking about
you.

SERENA
Nate. What we did was wrong.

NATE
Maybe we can make it right. Maybe we can - -

SERENA
Nate, listen to me. There’s only one way to make this right.
You need to talk to Blair.
(deep breath)
Tell her you don’t care about me, that you
never did. Say you’ll never see me again.

NATE
Why… why would I do that?

SERENA
Because. Because I’m asking you to.
(beat)
If you won’t do it for her, do it for me. Please.

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plz help :]]