Parenting Help. SOS

Help. My stepdaughter is 6 years old. Will be 7 in September. My husband is her full time dad and has been since she was 3. Mom is barely in her life due to drug abuse. Him and I have been together more than two years. The stepdaughter has been exhibiting behavior that is not right. It started in preschool, she would hurt animals and others students and show no remorse. In kindergarten, she tried to cut a girl's hair, called the teacher a loser, hurt people and laughed at them. Her teacher voiced how she is the mean girl of her class and the teacher's biggest worry was her lack of remorse and empathy. Now, in first grade, we have a dog that she openly admits to love to hurt him and likes to hear him cry, she punches students, slaps them, kicks in private parts, bullies them. Steals from the students and the teacher. Constantly lies and makes reasons and excuses for her actions and even tries to blame others for her wrong doing. She is narcissist, for sure and thinks that rules should not apply to her because she is a kid. And I'm due in October. I'm terrified. I fear that she will get worse and I fear for my baby. I don't know what to do, how to respond. No punishment nor reward motivates her and that is something even her teacher said. I'm just lost and scared and worried. Anyone? Please?(learn more on Glow: https://glowing.com)