The 42-year-old is furious with the 'Booty' hitmaker for sharing details of her heartbreaking split from the 'Gone Girl' star in 2005, just days before they were due to get married, reported Contactmusic.
"She's absolutely angry that J Lo has been discussing her relationship with Ben. Jen's livid that in almost every interview, she brings up how Ben was her first true love," a source said.
Affleck married Garner nine years ago and they now have three children together, Violet, eight, Seraphina, five, and Samuel, two.
The 'On The Floor'singer, who also wrote about their romance in her new book, 'True Love,' recently admitted she felt like her heart had been 'torn' out of her chest after her split from Affleck.