Ahogar means "to drown," and in this reflexive form, se ahogó translates to "it drowned" or "it sank". It's a dramatic word that paints a vivid picture of loss.
In the song, Ivan Cornejo uses this word metaphorically when he sings, "Donde nuestro barco se ahogó" (Where our boat sank). He's comparing his failed relationship to a shipwreck, a powerful and poetic image for a love that has been lost forever.
This song is one big, beautiful contradiction. Ivan Cornejo starts by asking his ex, "¿Quién crees que eres usted, maltratándome así?" (Who do you think you are, mistreating me like this?). He knows this person has all the power and even says "Te encanta destruirme" (You love to destroy me). It sounds like he's ready to leave, right? But then he completely flips it.
Despite the pain, he admits he's still completely stuck on this person. He doesn't care if people call him crazy for waiting, and he's still holding out hope for "nuestra parte dos" (our part two). The most heartbreaking line has to be when he says "Quiero olvidarme de ti" (I want to forget you), and then immediately follows it with "Y aquí te espero" (And here I wait for you). He's waiting right where their relationship ended, where their "barco se ahogó" (ship drowned), fully aware that their love might be a lie but willing to wait forever anyway.