'I Don't Understand What Happened:' Fiancé of Texas Mom Heidi Broussard Speaks Out

The fiancé of Heidi Broussard, the Texas woman who went missing in December with her newborn baby girl, has spoken out since police found her body stuffed in the trunk of her best friend’s car.

“She was the best mom, best person you could ever meet. She had like 25 best friends because everyone wanted to be her best friend. I don’t understand what happened, still,” Shane Carey told Good Morning America. 

Broussard and her 3-week-old baby Margo Carey were reported missing on Dec. 12. The infant was found in a Houston-area home Dec. 19, with her slain 33-year-old mother discovered inside the trunk of a vehicle on the same property. Margo has since been reunited with her father, who says he never suspected Broussard’s best friend Magen Fieramusca would be accused of the kidnapping.

“Heidi loved Megan. I mean, they had a great relationship. I went over in my head about 1,000 times; I should have been there. I should have noticed something,” Carey said.

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Fieramusca and Heidi Broussard, both 33, had been best friends for years since meeting at a Bible Institute when they were young. When Broussard gave birth to Margo on Nov. 26, Fieramusca was in the delivery room holding her hand.

At the time, Fieramusca had told friends she was 37 weeks pregnant and due around the same date as Broussard. However, authorities believe Fieramusca planned on kidnapping Margo to pass her off as her own.

RELATED: Kidnapped Baby Girl Is ‘In Very Good Health’ After Her Mom Heidi Broussard Was Found Dead

In early December, Fieramusca told the couple she had given birth days later, but she never sent them pictures or videos of her newborn girl.

The next week, on Dec. 12, Broussard was spotted on a neighbor’s CCTV camera getting into a car with Fieramsuca while holding Margo, according to an arrest affidavit obtained by PEOPLE. She would never been seen or heard from again.

“She was a friend, you know? Like, you would not suspect this at all,” Carey said of Fieramusca, who allegedly told her ex-boyfriend “don’t be mad, don’t be mad,” when she came back to the home they shared with a newborn girl.

RELATED: Woman Accused of Kidnapping Slain Best Friend and Her Newborn Allegedly ‘Wanted’ the Baby: Mom

Later, when her ex was shown a picture of Broussard and Margo, he told authorities, “That’s the baby at my house,” according to the affidavit.

Broussard’s body would be found in the trunk of Fieramusca’s car with Margo safe and alive inside. Fieramusca was arrested and charged with two counts of kidnapping and one count of tampering.

Her attorney could not be reached for comment Thursday.