Llamarada literally translates to "blaze" or "flare-up", often referring to a sudden burst of flame.
In this song, it's used metaphorically to describe a passionate and intense love that once burned brightly: "Cuando nuestro amor fue como llamarada" (When our love was like a blaze). It evokes a powerful image of a love that was once vibrant and consuming, now contrasted with the singer's current loneliness.
Diana Reyes's "Suerte Fatal" is a powerful song about the bitter end of a passionate love. The singer looks back at a time when her love was like a "llamarada" [blaze] and the light of heaven gave them joy. But now, all of that is gone.
She laments that her former lover will no longer call her to his arms, and she can't even tell herself that he might still kill her. The contrast between her past happiness and her current state is stark: she was so happy following his steps, but now she lives alone "como un criminal" [like a criminal]. It's a really intense way to describe the feeling of loss and isolation after a love has died.