An irate Long Island woman who fatally struck the grieving mother of an MS-13 victim sparked the deadly confrontation by trashing a memorial for the dead teen, the mom’s friends told The Post on Saturday.

The mother, Evelyn Rodriguez, who attended President Trump’s State of the Union Address earlier this year to bring attention to the slaying of her 16-year-old daughter, Kayla Cuevas, and Cuevas’ friend, Nisa Mickens, 15, was setting up flowers, balloons and photos on Ray Court in Brentwood for a vigil to mark the second anniversary of Cuevas’ death. The girls’ bodies were found in a nearby wooded area.

The angry woman, who has not been arrested or identified by authorities, had been trying for months to sell the vacant home adjacent to the memorial, and apparently blamed mourners who frequented the area for her inability to unload the property, mourners claimed.

She popped balloons, stole photos of the dead teen, dismantled a table, grabbed votive candles and threw the whole lot in the back of her white SUV, pals of Cuevas’ family said.

Rodriguez, 50, and her husband, Freddy, confronted the woman in an attempt to get back their property, the friends said. But instead, the woman tried to drive away and ended up hitting Rodriguez, police said.

The woman, who could not be reached for comment, stayed at the scene and called 911, said Suffolk County cops.

“They were just trying to retrieve their daughter’s picture, that’s what happened,” said family friend Noel Vega, 41. “How can somebody be so malicious and hostile over a memorial? On the anniversary of the day they found her dead daughter back in those woods. It’s bulls–t.”

A community activist visiting the scene Saturday was devastated by Rodriguez’s death.

“What happened yesterday was unnecessary, it was really unnecessary,” said Sammy Gonzalez, 57.

He remembered Rodriguez as a strong woman who was devoted to her anti-gang crusade.

“She was relentless in her fight against gangs and gang violence here. She was a wonderful, kind-hearted, but tough lady,” Gonzalez said. “What I want is to continue to her legacy and make sure gangs and gang violence is reported.”

Two Suffolk cops were stationed Saturday at the memorial site, which now stood vigil for Rodriguez and the two teens.