Someone walks beside the speaker through a terrible night, and the poem looks back on that time with a mix of gratitude and loss. The speaker was "out of my mind," and this other person, whether a lover, a friend, or something harder to name, took them by the hand and led them through the dark. The poem makes that dark double: it is the night outside and also the dark of a mind that has lost its footing.
What stands out is the line "The world around me was broken, but so was yours." The bond works because both people are damaged, so they understand each other. "Together we ruled" sounds almost triumphant, as if madness was a kingdom they shared.
Then recovery arrives, and the tone turns bittersweet. Being "sane" ends the pain, but it also ends the connection: "away went you." The short, rhyming last lines feel flat and quick, like a door closing. The mood is quiet, wistful, and a little uneasy, since getting better costs the speaker something they valued.