That's the Letter Duet between Susanna and the Countess.
Don't believe liking those kinds of opera arias qualifies as emo-ness, they're formidable compositions and that's why people enjoy them. Those two are gorgeous. Verdi and the Verists (Leoncavallo, Mascagni, Giordano, Catalani, Puccini, Cilea...) were gods of melody. I hate people who call them inferior and merely crowd-pleasing. They're crowd pleasing cuz they're damn good.
If you've just gotten into opera, I recommend you get your hands on Callas' recording of Puccini's Tosca. If you're free some afternoon, take the libretto which comes with the CD (original text and translation) and listen to the whole thing while reading it. You'll thank me later.
