Even by Adele standards, the degree of vulnerability on “To Be Loved,” the penultimate track of her new album 30, is unmatched. Originally envisioned as a mature explication of her divorce to her son, “To Be Loved” is a song so gut-wrenching that even Adele can’t contend with it; she’s left the room when it’s been played, and she’s vowed to never perform it live.

Part of this unprecedented vulnerability certainly has to do with Adele’s secret weapon, Tobias Jesso Jr. The co-writer and producer of “To Be Loved” had to follow up the overwhelming success of 25’s “When We Were Young,” so when the collaborators reunited for 30, they went back to the same studio and ended up with “To Be Loved.” Due to its subject matter and vocal difficulty, “To Be Loved” was laid down only after a few takes, an off-the-cuff masterpiece.

It’s evident that the stakes are higher for Adele than they’ve ever been before. “To be loved and love at the highest count/Means to lose all the things I can’t live without,” she sings. Jesso Jr.’s sparse piano comes in after Adele finishes her words, giving her vocal performance brighter poignancy and an even starker clarity. “I’m so afraid but I’m open wide/I’ll be the one to catch myself this time,” she says in a moment of comfort, and suddenly we remember that she’s here to let her son know just how difficult this separation is.

“To Be Loved” unfolds with the drama of an 11 o’clock number, and Adele’s untouchable delivery places it solidly among a pantheon of heartbreak songs. Wrapping up this painful testimony, she belts, “Let it be known that I’ve tried.” It’s the best she’s ever sounded.