Cordura translates to 'sanity' or 'good sense', describing a clear and rational state of mind.
In "Nana Triste", Natalia Lacunza sings, "Yo maldigo a mi cordura" (I curse my sanity), expressing the intense pain of being fully aware of her heartbreak. She beautifully uses this word to show that she wishes she could just lose her mind to escape the painful reality of the situation.
This song is a beautiful, sad lullaby for a relationship that has ended. Natalia Lacunza sings about wishing she could go back, saying, “Yo me quedaría contigo / Una, dos, tres noches más / Si no hubiera roto el hilo” (I would stay with you / One, two, three more nights / If I hadn't broken the thread). She remembers taking care of her partner like a child, singing “Te cuidaba como un niño / Que no sabe caminar” (I took care of you like a child / Who doesn't know how to walk).
But as the song goes on, the sadness turns into anger. What once “sabía a miel” (tasted like honey) now “supura y supura” (oozes and oozes) like a wound. By the end, she's not sad anymore; she's cursing her ex. The final lines reveal why: “Porque a un niño que no es mío / Nunca lo debí cuidar” (Because a child that isn't mine / I should have never taken care of). She realizes the relationship was one-sided and that she gave too much of herself to someone who couldn't give back.