Santana pours her heart out. It's something she's never done before but that's okay because she thinks if she can get her very soul laid bare for everyone to see, she'll be okay. She just needs Brittany to open her eyes and to understand.
When Brittany says she loves her back, Santana's heart lifts up into the air, but crashes back down a second later when he's brought into the picture.
Her soul rolls down her cheeks as she thinks that Brittany doesn't understand at all, not with her closed eyes and locked heart.