The holiday spirit took a beating at a YMCA on the Lower East Side, where witnesses said a family Christmas party went from merry to scary and cops wound up putting three women in cuffs.

A disagreement among the women in the Y at the Rutgers Housing project on Pike Street started at 1 p.m., and turned violent when grandma joined in and allegedly slugged a woman with a cane and bloodied her face, a YMCA staff member told The Post.

It was unclear what set off the fisticuffs.

“The girl that was fighting, her mother jumped in with her cane and just started bashing her face,” the staff member said.

Before the fight broke out, the women had joined in the merrymaking by getting their faces bedazzled and painted alongside their children.

A cop escorted the grandmother to a waiting police car — with a jewel bindi stuck to her forehead and blue and pink butterflies on her cheeks.

Meanwhile, a cane, not face paint, had colored the victim’s eye black and blue.

“Her eye was swollen shut right away,” the staff member grimaced. “She was bleeding a lot. Her face was cracked open.”

Mothers and children gathered for the fete, held in the small YMCA’s gymnasium, were part of a support group for domestic violence.

The women involved in the brawl had brought children to the party, witnesses said.

“[The victim’s] son was crying hysterically,” said the staff member. “He didn’t even want to look at her.”