In the 49-year-old entertainer's new YouTube video, titled "Making a Scene: Episode One" and published on Thursday, she details her experience of working with Fonda on 2005's Monster-in-Law and accidentally injuring her.
"Working with Jane Fonda was one of the highlights of my career," Lopez expresses. "She is such a powerful presence and so in the moment. It is everything you dream of when you're coming up as an actress and you think about working with the greats."
She then watches a scene where it's her character, Charlotte's, wedding day and Fonda's Viola refuses to wear her bridesmaid dress. The two then begin to physically fight, slapping each other and Lopez eventually punching Fonda in the eye.
"She really, really went for it. So did I and then I punched her in the eye by mistake," Lopez reveals. "I was so afraid to hit Jane Fonda in the face or hurt her in any way. And really, her character was very much like her and my character was very much like me. I was so afraid of her."
Lopez then details how they practiced their fight sequence, slapping each other until the scene "took a life of its own." "I don't even think we were supposed to slap each other," she says with a laugh, recalling that afterward, Fonda had a blood blister on the top of her eye. "My nail went up into her eye. I was mortified," she says.
The "On the Floor" singer goes on to share more memories from the set, as well as another scene she had with Elaine Stritch.
The almost 10-minute interview featured her kids asking what was the most trouble she got into when she was their age, if math is useless, which one of them is her favorite and if being a mom is different than she expected, among many other sweet and silly questions.
See more of the family interview, in the video below.