Boy, there's a lot going on in this episode. Here's what you missed:
In an attempt to break from formula, Mr. Shuster tries some new things for The New Directions' sectionals performance. The kids get upset with the changes and start taking it out on each other. Santana drops a bomb on Rachel (she hooked up with Finn before he dated Rachel!) and Rachel and Finn break up. Kurt is having trouble fitting in with the Dalton Academy boys and realizes that the grass may not be so greener on the other side.
Brittany loses Arnie's comb but he doesn't care because it wasn't really magical. Rachel and Kurt share a bonding moment together right before their performances which helps Kurt get through his.
The aging Hipsters get eliminated and New Directions ties with The Warblers so both of them move on, but for some reason Mr. Shuster takes the trophy back to his school!
Oh, and Emma got engaged to that dreamy dentist Carl.
So that's what you missed on Glee!