It wasn't always perfect, but it wasn't always bad,” Madonna sings on "Best Friend," a haunting slow jam from her 2012 album MDNA. The song is technically available only on the deluxe version of the record, but that doesn't make it any less potent. In fact, of all the tracks on MDNA presumably about Madonna's divorce from Guy Ritchie—and there are several —"Best Friend" is the most devastating. Not since Ray of Light has Madonna been this transparent in her work. "Your picture's off my wall, but I'm still waiting for your call," she continues. "And every man that walks through that door will be compared to you forever more."

These lyrics are simple, but they perfectly illustrate one of the stages of divorce: grief, mourning the loss of a relationship you thought would last forever. Full disclosure: I've never been divorced, but I imagine this is a key step in the healing process. It's also probably the hardest, which gives "Best Friend" even more resonance.

Couple this with the fact that Madonna is notoriously closed off. Any sign of vulnerability from her is novel, so for her to release a song like "Best Friend"—with lyrics like "I miss your brain, the way you think, but I don't miss the way you used to drink"—is jarring, to say the least. It shows no one is immune to the pain of divorce, not even the Queen of Pop.

"Best Friend" is, in many ways, the pinnacle of MDNA, which Rolling Stone dubbed a "disco-fied divorce record" upon its release in March 2012. To be clear, the album makes no direct reference to Ritchie, but it's obvious he's the inspiration. It's the first album Madonna released following her 2008 separation from the British filmmaker, and dozens of its lyrics explicitly discuss marriage.

"There are lyrics in here about custody and prenups and 'How'd you end up with all my jack?' Did you get a lot off your chest there?" journalist Harry Smith asked Madonna in 2012 about MDNA. Her response? "Yes, I did."

That's certainly an understatement. MDNA is, without a doubt, one of the most poignant divorce albums in contemporary music. It's EDM-oriented, sure, but Madonna's always been her most profound in a throbbing nightclub at 3:00 A.M. Underneath the swirling beats of William Orbit, Benny Benassi, and the other techno maestros who helped craft MDNA is a woman trying to make sense of her marriage ending.