My heart would break without you
Might not awake without you
Been hurting low, from living high for so long
I'm sorry, and I love you

from Lady Gaga – Dope Lyrics on Rap Genius

Meaning

This man is Gaga’s “dope”. Leaving him hurts, almost as if she’s gone into withdrawal, because she’s been so happy with him that she’s grown dependent.

By selecting this metaphor, Gaga is also addressing her actual, long-term battle with addiction. Which she’s indicated is a common theme through much of ARTPOP.
https://twitter.com/ladygaga/status/391995947841908736

To help improve the meaning of these lyrics, visit “Dope” by Lady Gaga Lyrics and leave a comment on the lyrics box