Two people are stuck at a crossroads, and the speaker is one of them. The poem opens with the plain admission that they are "trapped in between," then narrows the choice to two options: leave or stay. Neither one comes without pain.
What makes the poem sting is how it splits the hurt. If the other person leaves, "your heart will be broke." If they stay, "my heart will be broke." The speaker seems to believe that staying would cost the speaker something, perhaps because staying means holding on to a situation that isn't working, though the poem never says why. The grammar is a little rough ("broke" instead of "broken"), which gives the lines a raw, spoken feel, like something said aloud rather than polished.
The mood is quiet, tense, and stuck. The short lines and the mirrored structure make the dilemma feel like a closed loop. There is no resolution, only the sense that someone will get hurt either way.