Aborrezco comes from the verb aborrecer, meaning "to loathe" or "to detest." It's a strong and intense word for expressing extreme dislike, much more powerful than simply saying "no me gusta" (I don't like).
In the song, the artist uses this word to emphatically declare his profound hatred for his ex-partner, stating, "que la neta la aborrezco" (that honestly, I loathe her). This word choice highlights the depth of his negative feelings and the finality of their relationship, making it a memorable and impactful term.
Lefty Sm's "Diganle" is a super blunt breakup anthem where the singer is trying really hard to convince everyone (and maybe himself) that he's completely over his ex. He wants his friends to tell her that he's moved on, that his heart has healed, and that he's actually better off without her. He even says, "Que fue duro pero que bueno que se fue" [That it was hard but it's good that she left].
But as the song goes on, you start to hear a little crack in that tough exterior. He boasts about throwing a party when she left, but then admits he cried and almost went crazy. He even holds onto one last photo, asking himself, "¿por qué fui yo? El tonto que engañó, el tonto con el que jugó" [why was I? The fool she cheated on, the fool she played with]. It's a really interesting mix of trying to appear strong and letting some of that lingering pain show through.