Engañé comes from the verb engañar, meaning 'to deceive' or 'to trick'. While it can refer to deceiving someone else, in this song, it's used reflexively: me engañé.
This phrase, 'I deceived myself,' is particularly poignant in the lyrics. Paty Cantú sings about convincing herself that she could handle a casual relationship and that she was fine, only to realize she was wrong and had been fooling herself about her true feelings. It captures a moment of self-realization and regret.
Have you ever tried to convince yourself you're okay with something, only to realize you were totally wrong? That's exactly what Paty Cantú is singing about in "Fui Una Más" [I Was Just One More]. She thought she could handle a casual relationship, even telling herself, "Sé que jure que yo estaría bien" [I swore I would be fine]. But as the song goes on, it's clear she was just lying to herself.
She admits, "Te mentí, Me engañé, Pensé que podía manejarlo, Me equivoqué" [I lied to you, I deceived myself, I thought I could handle it, I was wrong]. It's a really honest look at how easy it is to get caught up in an idea of love that isn't real, especially when you've been warned. She knew he didn't believe in love, saying, "Me lo advertiste no escucharte fue mi error" [You warned me, not listening to you was my mistake]. In the end, she faces the truth: "Sé que al final del día solo fui una mas" [I know at the end of the day I was just one more].