The devastated mother of the 7-year-old boy killed when an out-of-control Mercedes SUV plowed into a Bronx eatery Thursday collapsed and cried in grief when she visited the scene of the fatal crash Friday afternoon.

“Oh, my god, my baby! Oh, god, why?” wailed Natasha Villavicencio, who had to be held up by two men when she arrived with about 20 others in front of the smashed storefront of the Kennedy’s Chicken and Sandwiches on Westchester Avenue, where her son, Ethan Villavicencio, was fatally struck by a hit-and-run driver.

“[The driver] took him away from me,” cried out the grieving mom, who relatives say was just across the street at a doctor’s appointment at the time of the crash. “[Ethan] was waiting for me.”

The tragic boy’s 5-year-old sister and the father were injured in the crash, which killed the boy as the family was eating at the chicken joint at 5:30 p.m. Thursday.

Maya, the boy’s sister, keeps asking for her big brother from her hospital bed, family members said.

“She’s OK. The only problem is she’s been asking about her brother,” said uncle Eddy Llamas – who also visited the crash scene Friday with the boy’s tearful 70-year-old great-grandmother, Haydee Latorre.

The car was driven by 73-year-old Kwasi Oduro, who smashed through the front of the eatery and fled, police said.

Llamas said the boy’s heartbroken father only wishes he was the one who died.

“The father is wishing it would have been him that died,” Llamas said.

The father suffered cuts to the head, and his daughter sustained wounds to her arm. They were listed in stable condition at Jacobi Medical Center.

Llamas said great-grandma Latorre is “heartbroken.” The older woman wept as she placed candles and superhero and sports-themed balloons at a makeshift memorial at the crash site. Other family members placed about a dozen plastic toy dinosaurs at the memorial.

Oduro didn’t get far from the crash scene before cops nailed him. He was taken to the 45th Precinct, and was awaiting arraignment at Bronx Criminal Court.