Honestly, I don't know. It could go either way. Maybe some elements are drawn from reality, while others are made up for the sake of the story. Without further research, it's a mystery.
Most likely not. 'Step Mom' is often a work of imagination by the writer or filmmakers. It might draw inspiration from real-life situations but is not a direct account of a true event.
Well, it could be or it might not be. To know for sure, you'd need to look into the background and the author's statements about it. Sometimes inspiration comes from real life, but the story gets embellished for entertainment.