given the rest of the song, i think the line should probably read (with proper punctuation)
That's when I know I should just drop everything and let her sing.
She's a better version of me.
You're expressing if there were a colon after sing, and then "she's a better version of me" would be what the unnamed girl the narrator speaks of would be singing. However, I feel if this unnamed girl were singing praises about the song's narrator, then it would go against the somewhat self-deprecating feel the song has to it.
gabbyownsme,
given the rest of the song, i think the line should probably read (with proper punctuation)
That's when I know I should just drop everything and let her sing. She's a better version of me.
You're expressing if there were a colon after sing, and then "she's a better version of me" would be what the unnamed girl the narrator speaks of would be singing. However, I feel if this unnamed girl were singing praises about the song's narrator, then it would go against the somewhat self-deprecating feel the song has to it.
Just my take.