Aguantarme comes from the verb aguantar (to endure, to put up with) plus the reflexive pronoun me, turning it into "to hold myself back."
In the line "Trato de aguantarme el llanto" the singer is struggling to keep his tears in, capturing that raw moment when you fight emotions bubbling up inside. It’s a memorable word because it combines a vivid feeling with a useful reflexive structure you can recycle in everyday Spanish.
This song is a straight-up, no-filter diary entry from right after a brutal breakup. Ivan Cornejo lays it all out, starting with the dramatic accusation, "Vida fue lo que me quitaste" (Life is what you took from me), leaving him with an "herida abierta" (open wound). He feels completely played. Everyone warned him not to give his all, but her "bonitas tus palabras" (pretty words) convinced him, and he ignored what everyone else could see.
Now, he's watching her live her life, seemingly happy, while he feels like he's dying. He wishes she could feel his pain, "pero más" (but more). It’s a really intense and honest line. He admits he's struggling to be strong and hold back tears, feeling like the whole experience is killing him slowly. The song ends with him facing the hard truth: "me toca aquí aprender a ya estar solo" (it's my turn to learn how to be alone now).