What episode of Glee does Darren Criss (blaine) come out as gay?

okay, So i was watching the glee marathon and I havent seen all the episodes of the second season. I'm just wondering, what episode did Blaine actually say he was "gay".. Like was it known. For an example. When we watch Kurt, It's obvious he's gay. And he even said it himself in the show... So when exactly did blaine say it?