Gwyneth Paltrow is known for her strict diet and healthy lifestyle. But insiders tell In Touch that when the GOOP founder discovered her ex-husband, Chris Martin, got back together with Jennifer Lawrence, she threw all that out the window and started chain-smoking!

The "meltdown," according to In Touch's source, happened on Oct. 31 – after Jennifer was spotted back at the Coldplay rocker’s Malibu home on Oct. 27, and again on Oct. 30.

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On her way to a photo shoot on Halloween, Gwyneth was so on edge she started smoking and even tried to get her driver to stop for a drink so she could calm her nerves, the insider tells In Touch. “She never smokes or drinks like that,” the insider adds, “so everyone knew something was up.”

“She was a mess all day,” the insider says of Gwyneth, who last year declared that she allows herself to smoke a single cigarette every Saturday night. (Oct. 31 happened to be a Friday.) She was chain-smoking, says the insider, and “started frantically texting Chris.”

For more on Gwyneth’s breakdown, including details about the renewed romance between J-Law and Chris Martin, pick up the new issue of In Touch, on newsstands now.

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