The sky could fall, could fall on me
The parting of the seas

Since this song is supposed to be in Kurt's POV and it's right before the "you mean more to me than any color..." line, I see it now more as:

"I could pay for the choices I make; in being your friend, in protecting you from other people."
The significance of using the phrase "the sky could fall on me" could be that Kurt is trying to word it in a childish metaphor that Dorian is familiar with. And it follows the plot in that when Kurt is well aware the others are tormenting him, he very gradually dims out as that perfect, outgoing, social person. He could very well antagonize himself at Spiraling Summit because of his anger for a friend's hardship.