Exagerando is the Spanish equivalent of "exaggerating". This word is a perfect example of a cognate—a word that looks and sounds similar in both Spanish and English—making it easy to remember.
In the song, the singer uses it to add weight to his feelings, insisting, "Te juro que no estoy exagerando" (I swear I'm not exaggerating). He's emphasizing the raw, desperate truth of his emotions, making this a key word for understanding the song's passion.
Ever been through a breakup where you just don't know what to do next? That's exactly what Banda MS is singing about here. The singer is going back and forth, wondering, "A lo mejor te olvido / A lo mejor jamás" (Maybe I'll forget you / Maybe never). He might call, he might not. He even admits something pretty extreme: "te juro que no estoy exagerando / Cuando te digo que sin ti soy nada" (I swear I'm not exaggerating / When I tell you that without you I'm nothing).
But then he gets to the heart of it. He remembers his ex telling him that being with him "no valía la pena" (wasn't worth it). So he throws down a challenge. He asks, "quién olvida el amor de su vida / En un par de días" (who forgets the love of their life / in a couple of days?). He decides that if his ex can move on that fast, then it proves one thing: "Nunca fui el amor de tu vida" (I was never the love of your life).