Earlier this week, the couple announced they will be stepping away from their roles as senior royals and will work to become "financially independent" while still "fully supporting" the Queen.
Samantha, who has spoken out against Meghan on several occasions since she got engaged to Harry, branded their announcement "attention-getting" on Thursday.
Speaking to Inside Edition, Samantha said: "It is a slap in the face. I think what is shocking is the lack of consideration for the people involved, the British royal family, the promises that were originally made to honor royal duties and to lead by example."
Clearly she knows she's engaging in attention-getting behaviours.
When asked why blame them for wanting a private life away from the spotlight, Samantha continued: "That's ridiculous. They stepped into the spotlight knowing what the duties were and knowing what the media would be like for them.
"If she wanted to be so private, she wouldn't have sat at Wimbledon with 40 empty seats around her. Clearly she knows she's engaging in attention-getting behaviours."
When asked if she thinks she could "mend" her relationship with Meghan after she and Harry revealed plans to balance their time in the UK and North America, Samantha didn't seem keen.
She said she doesn't plan on reuniting with her sister because of "the way she's treated this family, our family and the royals".
Samantha said she thinks it's "horrendous how we've been treated" and she wouldn't want to "associate with anyone who could do this to people so easily".
On their official website, Meghan and Harry said they are planning to continue their work in the Commonwealth and charitable organisations.
Following their announcement to step down, Buckingham Palace officials later described the move as "complicated".
They said in a brief statement: "Discussions with The Duke and Duchess of Sussex are at an early stage.
"We understand their desire to take a different approach, but these are complicated issues that will take time to work through."
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