I realized something just now, re-watching this on YouTube.
It was reported that Lea Michele actually came in and recorded this song/scene before anything else; and after she did, it was like she was giving her “blessing” for everyone else to make the episode as well. She was even quoted saying something along the lines of: “This won’t be any harder for anyone else than it was for me”
And she was damn right.
Think about this: This is a STUDIO recording. It is supposed to be crisp, clean, the best version the artist records of the song. And about a quarter into the song, there is an audible sniff from Lea. Now granted, I’m sure she didn’t do more than one MAYBE two takes of the actual recording, but it is still left in.
Now to the actual scene itself: What we’re ACTUALLY watching, is the first time that the entire cast is sitting in the choir room together, without Cory, watching their friend Lea mourn him. And what we are witnessing is each ACTOR breaking down themselves about the loss of their friend Cory, not so much as the characters mourning Finn.
What we’re watching is Lea Michele saying goodbye to her “person”, raw and in front of the entire world to see.