We live in a close-knit community. Thirty houses surrounding a square of garden that is perfect for our kids. We congregate here on major holidays, each family bringing a plate and sharing food and conversation. It's in the garden that I first met her. The woman who would worm her way into my family and piece-by-piece tear it apart ...

I should have known something was wrong from the very beginning. She seemed perfect in so many ways: she floated through the baby shower, a warm smile on her face, chatting to strangers with ease. At first I thought it was sweet that she offered to help me, that she made an effort to get to know us, that she brought over games and knew Luna's favorite foods ... I had no idea that I couldn't trust another mother ...

I should have known that someone would eventually discover the secret in my marriage. Why I never believe a word my husband says—and why he shouldn't believe me. But how could a woman I only just met be the one to find it out?

If I'd known, I'd have called the police sooner.

And maybe I'd have prevented that dreadful scene. Every neighbor peering through their curtains as the sirens wailed in our street.

I could have protected my family.

I could have stopped what happened next ...