Condenarme means "condemn me" or "sentence me". It's a strong and dramatic verb that conveys a sense of being trapped or doomed by someone else's actions.
In the song, the singer uses it to express the profound impact of his lover's departure, singing, "Y condenarme a tus besos usados" (And condemn me to your used kisses). This powerful imagery suggests that her leaving not only causes him pain but also leaves him with the lingering, perhaps tainted, memory of their past intimacy, making it a truly memorable and emotionally charged word.
"Si Te Vas" is a plea from someone watching a relationship slip away. The singer opens with the line that gives the song its title, "Dime que te vas" ("Tell me you're leaving") — he says he'd rather hear it said outright than keep loving someone who has already checked out: "Prefiero eso a sentir que te tengo, pero ya no estás" ("I'd rather that than feel like I have you, but you're not here anymore").
The chorus turns into open bargaining. He isn't asking her to stay for good, just for one more night: "Solo te pido quédate una noche más" ("I'm only asking you to stay one more night"), so he doesn't have to face her leaving in his dreams. He wants the truth about why she's going, and warns her she won't find love like his anywhere else: "Te di mi amor, no te lo vayas a robar, por que como yo, nunca jamás te van a amar" ("I gave you my love, don't go stealing it away, because no one will ever love you like I do").
The bridge is the most direct moment, admitting how much this is costing him: "Yo me estoy muriendo, tú me estás matando" ("I'm dying, you're killing me"). From there he presses her for real answers — how much longer she'll keep playing with his heart, and what she actually wants after all the unanswered questions and used-up excuses.