Contaminante translates to "contaminating" or "pollutant." It's an interesting word choice because it's not typically used to describe a person in everyday conversation, making it stand out.
In the song, the artist uses it metaphorically to describe a person's presence as something harmful or toxic, singing "En mi vida contaminante con tu ser" (In my life, contaminating with your being). This strong, evocative word conveys deep negative feelings towards the person who left, suggesting their presence was detrimental.
Polo González's "Te Fuiste" is a really interesting take on a breakup! It starts with the singer admitting, "que sufrí cuando te fuiste" [that I suffered when you left], but quickly pivots to a blunt acceptance: "pero así lo decidiste" [but that's how you decided it]. He even says, "me dejaste a que muy triste esto con chistes" [you left me very sad, this with jokes], almost making light of his own pain.
But don't be fooled, this isn't just about sadness. He's actually quite relieved, calling his ex a "contaminante con tu ser" [contaminant with your being] and saying, "qué bueno que te alejas en mi vida" [how good that you're leaving my life]. He's enjoying the fact that she's now watching his profiles and getting upset, declaring, "tú sola te estás dañando, estoy disfrutando" [you alone are hurting yourself, I'm enjoying it]. It's a song about moving on, finding joy in freedom, and maybe a little bit of sweet revenge.