Cicatriz translates to "scar." While it can mean a physical mark, it's often used in a poetic way to describe deep emotional wounds that remain after a painful experience.
In this song, Junior H uses it to create a powerful, bittersweet image, singing "Y quedó la cicatriz / De miles de rosas" (And the scar of thousands of roses remained). This beautiful line suggests that even a relationship filled with grand, romantic gestures ultimately left a permanent mark of pain.
This song is one of the most direct breakup anthems you'll ever hear. Junior H isn't just sad; he's wishing his ex a miserable life without him. He kicks things off with the incredibly blunt line, "Espero no seas feliz / Cuando tú ya estés sin mí" (I hope you're not happy / When you're without me). He looks back on their relationship as a "cicatriz / De miles de rosas" (scar / from thousands of roses), a beautiful thing that ended up leaving a permanent mark.
He's convinced she left him for someone with more money or stability, telling her, "Si te asegura tu futuro, quédate ese cabrón" (If he secures your future, stay with that bastard). He then predicts her new life will be empty, that the new guy won't comfort her when she cries or write her a whole song like he would. The core of his pain seems to be in the chorus: "Tenerte es bien fácil / Y amarte, difícil" (Having you is very easy / And loving you, difficult). It suggests that while their physical connection was simple, a real, deep love was impossible, and that's what left his "corazón frágil" (fragile heart) in pieces.