Texas Tragedy: Jessica Simpson's Cousin Killed In A Car Crash Nearly 20 Years Ago –– Singer Still Haunted By The Death

Jessica Simpson is haunted by a painful family tragedy -- the death of her cousin when they were teenagers, and her friends fear for her as the anniversary approaches.

"Jessica's haunted by the accident that took her cousin Sarah's life," a family insider divulged to The National ENQUIRER. "While the tragedy happened in 1996, not a day goes by when Jess doesn't think about it."

Sarah Hering -- who was then 17 -- was riding in the passenger seat of her boyfriend's pickup truck as they drove down a rural Texas road near Waco in May 1996. According to a local news report, a "runaway horse was from a local rodeo ... darted in front of the vehicle" and "upon impact, the horse came over the hood crashing into the windshield."

According to the insider, "Jessica saw Sarah as a big sister" and "someone she looked up to as a young kid."

The two "were inseparable growing up, and had so many plans that involved each other."

The two "even talked about going into the fashion industry together," a business Jessica has thrived in since her rise to fame.

At the funeral, the teenage Simpson sang "Amazing Grace" as a tribute to her cousin, the source said, adding that "there wasn't a dry eye in the church."

Later that year, Simpson dedicated her self-titled album "Jessica" to Sarah.

Each year since then, family members have been concerned about Simpson, now 34, around the anniversary of Sarah's death. This year, they're especially worried after recent reports said the mother-of-two has become struggling with prescription pills and booze as she struggles to stay thin.

"Even after 19 years, Jessica is still coping with her cousin's death," the source said. "Every time Jessica goes back to Waco to see family, she visits Sarah's grave.