Meghan Markle is not going to show that she's upset and bothered about an upcoming book release from her sister, Samantha Markle, but sources claimed that the Duchess of Sussex is feeling "sick to her stomach" about The Diary of Princess Pushy.

 Samantha warned that her book, out in the U.S. on Feb. 1, will make Meghan uncomfortable and it will be good that she has her husband, Prince Harry, to support her. A source said that the Duke of Sussex has never believed anything Samantha has said about his wife in the media.

Meghan's sister has been outspoken about her criticisms since the world discovered the former TV star's royal romance with Harry in 2016. Samantha, who is based in Florida, has appeared at various TV shows in the United Kingdom to slam her sister and her actions as a member of the royal family.

Samantha was never invited to Meghan and Harry's royal wedding because they apparently do not have a relationship. Growing up, Meghan and Samantha had a few instances of gathering together as a family, but the two sisters haven't bonded together, according to royal biographer Omid Scobie.

But amid the buzz and anticipation of Samantha's book, she told Us Weekly that it's not going to be a tell-all, despite what others might expect. Samantha said that she didn't write The Diary of Princess Pushy to attack Meghan, but the book will have stories about the "good, the bad and the ugly" of being in an interracial family.

Meghan and Samantha share the same dad, Thomas Markle, but the latter's mom is Caucasian Roslyn Loveless Markle. Samantha has been estranged from the duchess years before she was to marry a member of the British royal family.

Samantha is also estranged from her mother and her brother, Thomas Markle Jr, as well as her three adult children. Her mother spoke against her following her frequent attacks on Prince Harry's wife in the media. Roslyn said that Samantha's behavior was embarrassing for the family.

Meanwhile, Meghan and Samantha's dad said that he's pleased about the book release and is eager for his oldest child to talk about her work in the media. Since their fallout before her wedding to Harry, the Duchess of Sussex hasn't spoken nor seen her father since their fallout. The Sussex's son, Archie, has yet to meet his grandfather as well.

But Roslyn also said that Meghan should never let Thomas into Archie's life as he "cannot be trusted." Samantha's mom was married to him for 11 years, but she claimed that he repeatedly cheated and verbally abused her. Thomas has denied his ex-wife's claims.