The vengeful sister-in-law who doused a UK bride in black paint spilled the details on the messy family feud behind what she branded a “spur of the moment” attack.

Antonia Eastwood – sentenced last week for the spite-fueled May 2024 outburst aimed at bride Gemma Monk – told the Daily Mail that she is “ashamed” of what happened at the Maidstone wedding, but claimed simmering tensions and jealousy between them had been brewing for years.

The 49-year-old hairdresser claimed the blazing rivalry began when she started dating Monk’s brother in April 2023.

The pair married just five months later – but Eastwood said setting the date sent Monk into a jealous spiral, as her partner of more than 20 years still hadn’t asked her to tie the knot.

“After that, Gemma started coming round and talking about Ash’s past girlfriends,” she told the outlet.

“She’d say, ‘Aren’t you bothered about all those other girls?’ I kept telling her I wasn’t jealous of Ash’s past. I knew what she was doing wasn’t right, but she was part of my soon-to-be husband’s family.”

Monk, 35, also admitted “bad blood” between them, noting she “didn’t warm to” Eastwood “that much.”

Eastwood claimed her new sister-in-law then set out to sabotage her wedding – with Monk ousting her longtime beau as best man and then trying to trip her as she walked down the aisle.

Monk denied the “ridiculous” tripping attempt, stressing she isn’t tall enough to do it “even if I wanted to,” and pointing to wedding footage that shows Eastwood walking past her “without any incident.”

The bitter fallout escalated further when Monk banned her brother and his new wife from her nuptials a year later – but the pair still showed up.

Eastwood said she intended to give the bride a “piece of my mind,” the outlet reported.

Eastwood then found her daughter’s tub of “child-friendly” black paint in the car upon arriving – which she claims was a coincidence – before hurling it at Monk just moments before she walked down the aisle. 

“I saw [Monk] get out of her car – she was a few yards away,” she said.

“Then I just shouted to her and threw the paint. It hit the back of her dress. I don’t know why I did it,” Eastwood added, claiming the cruel payback was a “spur of the moment thing.”

Shocking photos showed the crestfallen bride-to-be with dark, mud-like paint covering the left side of her face and chest and spattered across her white wedding dress.

Monk then grabbed her twisted attacker’s hair before Eastwood bolted and fled with her husband back to Greater Manchester, where the couple lives, the Mail reported. 

Remarkably, Monk was able to compose herself, clean up, get a second wedding dress — and tie the knot just two hours later.

“We had waited for that day for so long. Nothing was going to stop me,” Monk said after her sister-in-law was found guilty of criminal damage on April 15.

Eastwood was handed a 10-month prison sentence, suspended for 12 months, the UK equivalent of parole. She was also ordered to do 160 hours of community service.

She said the entire explosive experience has “taken its toll.”

“I had a full-blown panic attack on the day I was sentenced” Eastwood told the outlet, adding she was “petrified” of being locked up.

“I feel ashamed of myself. It’s not me. I’ve never been in trouble with the police before. Ever.”