My shadow wants to harm me

This was a random conversation that took place yesterday when I mentioned to a friend that I used to see another me in my dreams. I described her as a psychopath and a sadist that knows no remorse. Her intent is to take over and in my dreams she would repeated harm me. Sometime it was ripping my tongue in half, others draining my blood. I never gave it much thought other than some disturbed dream perhaps triggered by something I watched that I then internalised. Now I question that because I dreamed of her even as a young girl. She’s evil and her sole intent and focus is my destruction. I didn’t even connect it to my ‘shadow’ until my friend pointed it out. If for argument’s sake it is, how may that be interpreted? What does it mean and how do I begin to even work on that? All I know is, is that the very thought of her TERRIFIES me.