My 19-year-old babysitter asked if the other Mrs. Calder needed her Pyrex casserole dish back. I had been divorced from Nathan for 8 months, and he swore his custody nights were just him and the kids. Then she said, She answers the door there. At 7:10, I sat parked across from his townhouse with my old casserole dish in my lap.

Jenna was 19, a sweet kid from our church who wore glitter nail polish and always overfed my children.

She watched Lily and Ben after school on Tuesdays, then drove them to Nathan’s townhouse when it was his custody night. I paid her cash on Fridays because she was saving for community college and hated waiting on bank transfers.

That Tuesday, she came to my kitchen at 4:36 with Lily’s backpack, Ben’s muddy hoodie, and a round Pyrex dish with a red plastic lid.

Is this yours or the other Mrs. Calder’s? she asked.

I was rinsing grapes at the sink. The water kept running after my hands stopped.

I said, What other Mrs. Calder?

Jenna’s face changed. She looked like a kid who had stepped on a grave without knowing it.

Oh. I thought… I’m sorry. The lady at Mr. Nathan’s.

I turned off the faucet. The kitchen smelled like wet grapes and the dish soap I buy at Dollar General because it does not tear up my hands.

I asked Jenna to sit down. She did not want to. I could see every adult instinct in her telling her to leave the room and never answer another question. But she loved my kids, so she stayed.

She told me the woman had opened Nathan’s door 5 times. Not once. Five. Brown hair, silver hoop earrings, white SUV in the driveway. She knew Ben liked ketchup on macaroni. She had signed Jenna’s pickup slip one night when Nathan was still on a call.

Jenna said, She told me to just call her Tessa.

Tessa. Nathan’s project manager at Tri-State Flooring was named Tessa Rourke. She had sent me a baby gift when Lily was born. A yellow blanket with ducks on it.

I am not proud of what I did next. I asked Jenna questions like a lawyer and she answered like a witness. Dates. Times. Which nights. Whether the kids seemed upset. That last one was the only one that made her cry.

Ben asked if she was moving in, Jenna said.

Ben was 6. Nathan had stood in mediation and told the judge his home was stable and child-centered. He had told me I was too anxious to co-parent peacefully.

The twist was the casserole dish. My name was still taped to the bottom from a church potluck 3 years earlier. Nathan had let Tessa serve my children dinner in my dish.

At 6:22, I texted Nathan: Are the kids with you?

He replied at 6:24: Of course. Movie night. Stop checking up.

At 7:10, I parked across from his townhouse on Larkspur Court. His porch light was on. Tessa’s white SUV sat crooked in the driveway. I could see the kids’ shoes by the door through the front window.

I did not go up right away. I called my attorney, Susan Meeks, and she told me to breathe, take pictures of the vehicles, and not create a scene Nathan could use against me. So I sat there with that casserole dish warming in my lap and my phone on my knee.

At 7:38, Nathan’s front door opened. Tessa stepped out wearing my old gray college sweatshirt. Then Ben came running after her, holding a school paper I had never seen. Tessa bent down, kissed the top of his head, and said something that made him nod.

I opened my car door just as Nathan stepped onto the porch and saw me. He did not look scared. He looked annoyed.

Then Tessa turned, saw my face, and said, Nathan told me you already knew.