Vacilando is a versatile word that can mean 'hesitating', 'wavering', or even 'messing around' or 'flirting' in a casual way. It's a great example of a word with multiple layers of meaning depending on the context.
In this song, IZA uses it to express frustration with her lover's indecisiveness and playful teasing. She sings, "'Cê 'tá vacilando me deixando assim," implying that their partner is messing with her emotions and leaving her in a state of confusion and longing. It captures the push-and-pull dynamic of a complicated relationship.
IZA opens this one with a scene straight out of a movie: a note written in lipstick on the mirror that reads, "Não me procure, me esqueça" [Don't look for me, forget me]. She's the one who walks out the door, but she isn't gone for good. By Friday she's already circling back to check on him, because as she puts it, "Vou dar um tempo pra 'cê pensar" [I'll give you some time to think].
The song works because it flips the usual breakup script. Instead of begging to be missed, IZA is the one keeping score, watching for the moment "O tempo faz você se tocar" [time makes you realize] what he lost. By the chorus she isn't asking anymore, she's stating a fact: "Você não vive sem mim" [You don't live without me]. It reads less like a plea and more like a victory lap, and that confidence is the whole appeal.