Espejismo translates to "mirage". It's a captivating and somewhat rare word that evokes a sense of illusion and deception.
In the song, the singer uses it to describe her past relationship, saying, "fue un espejismo lo que viví" (what I lived was a mirage). This powerfully conveys that her love and happiness were not real, but rather a deceptive illusion, making it a very poignant and memorable word in the context of heartbreak.
María José wrote this one for the exact moment you stop believing the lies. She opens with 'Esta es la ultima vez que me prometes lo que no es' [This is the last time you promise me what isn't true], already past pleading and into done. The picture she paints of him is specific: he's changed into someone else entirely, 'Te has convertido en otro ser, tan diferente al hombre que yo ame' [You've turned into another person, so different from the man I loved], and no apology fixes that.
The chorus says the whole thing in one line: 'Lo que tenías conmigo, hoy ya no tiene sentido' [What you had with me makes no sense today]. She names the other woman too, singing 'Con ella hiciste todo lo prohibido' [With her you did everything that was forbidden], and by the last chorus she sounds less wrecked than free: 'Y ahora no tengo miedo de volar, no vas a detenerme ya' [And now I'm not afraid to fly, you won't hold me back anymore].