Desahogo literally means "relief," "release," or "outlet"—the act of unburdening oneself. It's a beautifully expressive Spanish word that you won't hear every day.
In this passionate bachata, the singer tells his lover to inform her other man, "Que soy tu desahogo" (That I am your outlet). He is her escape and her confidant, the person she turns to for emotional and physical release from her unsatisfying relationship. This word perfectly captures the drama and intensity of the song's love triangle.
This song is a masterclass in confidence! El Chaval isn't just a passive lover waiting on the sidelines; he's actively coaching his partner on how to dump her old boyfriend. He gives her a whole script, telling her to say, "Que ya tú no lo quieres / Que tienes otro hombre / Que por ti se muere" [That you don't love him anymore / That you have another man / Who would die for you]. It's a total power move. He wants her to make it clear that he has completely won her over, declaring, "Dile a él que yo le gane la guerra" [Tell him that I won the war].
And the details get wilder from there! He tells her to say he's her "ginecólogo / Cuando estamos a solas" [gynecologist / When we're alone]—a very blunt and unforgettable way to describe their intimacy. He's not just her lover; he's her addiction ("eres mi droga" [you're my drug]) and her emergency contact, the "911 de tu emergencia" [the 911 for your emergency]. The song is basically a victory lap, a set of instructions for his lover to announce his total triumph.