The bleeding woman at the center a wild Long Island high school graduation brawl is nearly four months pregnant — and she told The Post it was a family feud that started on Facebook.

Bianca Bouchard, 21, who is 15 weeks pregnant, was whacked and kicked in the head outside William Floyd High School in Brookhaven on Sunday during the melee, she said.

Bouchard can be seen in an online video of the fracas bleeding from the right side of her head after she was attacked while lying on the grass.

“My head is sore, but I’m fine,” said Bouchard, who only suffered a scratch to the back of her head. She said she doesn’t know the woman who kicked her, but said the brawl was a family feud that initially started on Facebook between her 15-year-old sister and another relative through marriage.

“My sister fought one of the girls who was graduating,” she said. “We always got along. My sister and the other girl had been going back and forth on Facebook.”

Bouchard got caught up in the mayhem after trying to defend her younger sister.

“It was crazy,” said Bouchard, who was at the ceremony for her sister’s boyfriend who had graduated.

“I didn’t feel like ruining anyone’s graduation. It did happen after [the graduation] was over and it just got crazy,” she said.

Police are investigating the incident.