desconsolado is a powerful adjective that means 'inconsolable' or 'heartbroken'. It comes from the root consuelo (comfort), so to be desconsolado is to be in a state where one cannot be comforted.
In the song, Marc Anthony belts out "Te lloré, desconsolado" (I cried for you, inconsolable), using this incredibly expressive word to paint a picture of his absolute despair after the breakup. It's the perfect dramatic word for a classic salsa heartbreak anthem.
This is one of the all-time great 'you messed up' songs. Marc Anthony's ex has suddenly reappeared, wanting to talk and go to dinner because, as he puts it, "Tal parece que yo te hice falta de más / Que no fuiste feliz / Con tu otra mitad" (It seems you really missed me / That you weren't happy / With your other half). She's crying, saying she never forgot him, and acting like she can just pick up where they left off.
But she forgot one tiny detail. When she left, he was "libre para elegir" (free to choose), just like she was. And choose he did! The chorus hits with the big reveal: "Y hubo alguien" (And there was someone). While she was off living her life, someone else stepped in, someone who "se moría por llenarme de detalles / Y palabras amables" (was dying to fill me with details / And kind words). He tells his ex, with some satisfaction, that he gave this new person his body, soul, and mind. The song ends with him repeatedly telling her, "Y ahora no puedes vivir sola sin mí" (And now you can't live alone without me), twisting the knife just a little bit more.