Chingaos is a very common colloquial and somewhat vulgar Mexican Spanish interjection, similar to "damn" or "heck" in English. It's often used to express frustration, surprise, or to emphasize a statement.
In the context of the song, the line "cĂłmo chingaos que no" (how the heck not) is a strong, informal way of asserting confidence and dismissing any doubt, adding a touch of authentic, regional flavor to the lyrics.
"Ya No Vuelvo Contigo" is a breakup song about closing the door on a relationship for good. The singer starts by remembering small, intimate details, the scent of a pillow, a certain look, the kisses they used to share, then makes the decision plain: he's not going back.
He admits the love once felt real, with real hopes and passions, but accepts that it simply didn't work between them. Rather than dwelling in anger, he leans into acceptance, calling it fate and saying only the moon is left as witness to everything he once felt.
Midway through, a spoken aside breaks the mood with a touch of humor and swagger before the song returns to its chorus, repeating the same resolve: it's over, and moving on is the better path.