Envolviste comes from the verb envolver, which literally means 'to wrap' or 'to envelop'.
In this heartbreaking song, Selena sings about how a deceitful lover wrapped her up in a beautiful illusion ("Me envolviste dentro de aquella linda ilusión"). She uses this word metaphorically to describe being completely surrounded and captivated by false promises, making it a vivid and poetic way to express a romantic betrayal.
Have you ever given everything to someone who swore you were their cure, only for them to vanish into thin air? That is exactly the kind of mess Selena calls out in this Tejano track. She looks back on a guy who promised he would return, swore he would stop pining over another woman, and claimed she was "la medicina para tu dolor" [the medicine for your pain]. She bought the fantasy and jumped in completely unconditionally ("sin ninguna condición"). But time passed, he ghosted her, and now he won't even face her.
Instead of sitting around weeping, she pulls zero punches and labels him what he is: "Cobarde, tú no eres más que un cobarde" [Coward, you are nothing more than a coward]. She calls him out for literally running away because he lacks the guts to look her in the eyes ("Te falta valor para hablarme" [You lack the courage to speak to me]). Even while he stays on the run, she tosses out a sharp, self-assured warning: "más temprano que tarde / Te vas a acordar bien de mí" [sooner rather than later, you will remember me well]. The common idiom más temprano que tarde literally says "earlier than later," which works just like the English phrase "sooner or later." It gives her the ultimate last word over a runaway ex who could not keep his word.