Britney Spears and Christina Aguilera have had a very up-and-down relationship since they performed together as Mouseketeers in The Mickey Mouse Club in the mid-1990s.

In Spears' memoir, The Woman in Me, now available, the "Toxic" singer Aguilera describes her "Justified and Stripped Tour" with Justin Timberlake in 2003, and Spears and Timberlake's breakup Only a year later, Aguilera and Timberlake jointly condemned their appearance on the cover of Rolling Stone.

"They were on the cover of Rolling Stone together, him in a black tank top and staring at her with sexy eyes, and her in a lace-up black shirt staring into the camera," Spears wrote in her new book.

"In that article, she said she thought Justin and I should get back together.

"Even if they weren't trying to be cruel, it felt like they were just pouring salt in the wound. Why is it so easy for everyone to forget that we are all so vulnerable that these headlines leave bruises?

Elsewhere in the memoir, the Daily Mail praised Spears for Aguilera, saying she seemed "really professional on TV" when she was on "The Voice" in 2016. However, the author of "Woman in Me" did not mention the "Genie in a Bottle" singer's involvement in a 2003 VMA stunt in which Spears and Madonna kissed on stage and Aguilera stood nearby.

According to the Mail, Aguilera said in an interview with Blender after the VMAs that Spears "seemed nervous the whole time" before the stunt and described her as a "lost girl, someone who needed guidance."

Not surprisingly, Spears was not thrilled with this description, later telling Blender.

Asked last week if she thought she would appear in the memoir, Aguilera told Jimmy Kimmel, "Hey, I don't know," (via Billboard).

When asked if she hoped Kimmel would appear in that memoir, she replied, "I don't know! I don't know! I mean, I hope all is well with her and everything is beautiful. I think the future should be blessed."

"Woman in Me" is available for purchase below or where to buy the book.