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.
Ivan Cornejo jumps straight into the mess of a toxic breakup here, calling out an ex who walked all over him while he did everything for them. He opens with pure frustration, snapping, "¿Quién crees que eres usted, maltratándome así? Piensas que soy un pendejo haciendo todo por ti" ("Who do you think you are, mistreating me like this? You think I'm an idiot doing everything for you"). The word pendejo is very common Mexican slang for a fool or an idiot, and he uses it to admit he let himself get played. Even though he knows this person loves to destroy him and holds all the power, he cannot break the spell. He compares their broken relationship to a sunken ship ("donde nuestro barco se ahogó" / "where our ship drowned") and asks when their "part two" is coming out, as if their romance was a movie waiting for a sequel.
The real punch of the song is how honest he is about his own foolish hope. People call him crazy for thinking she will come back, but he does not care. He admits he lied when he said he felt nothing, confessing, "Y aunque sea mentira tu amor, te esperaría todo el tiempo en el mundo" ("And even if your love is a lie, I would wait for you all the time in the world"). He is stuck in the exact spot where everything ended, torn between begging for her return and begging his own brain to just forget her.