She started off the rant by going after Harry. While he tweets are protected based on her privacy settings, The Daily Mail managed to snap pictures of each of them.
"Harry is a 'wuss' to allow the Duchess of Nonsense to mistreat everyone who has been close to her, especially her family," the 53-year-old wrote. "Diana would be ashamed. Stop wearing Meg's skivvies and bra and take your pants off of her!"
She also tweeted an image of British actress and model Cressida Bonas, Harry's ex-girlfriend, and said Harry should have married her instead of Markle.
"She is much more like Diana," Samantha wrote. "That's who Harry should have married."
The mother-of-three also fought back against the critics, calling her actions "tough love."
"Sorry tough love exists and just because I can speak out about some things does not mean I don't love her but I can call out things I do not agree with... if nobody lies it it's too damn bad."
Samantha has spoken out against the Duchess of Sussex numerous times in the past. Back in April she criticized Harry and her for not inviting any of her family members beyond her parents to the royal wedding in May.
"Smoke and mirrors cannot hide the elephant in the room," she wrote. "Out of respect, tradition and humanitarianism, the (Markles) should be invited if 2,000 complete strangers are invited. Our uncle who got her the internship, brother, me, best friend of 30 years Nikki Priddy, nephews. Fact."
Days before the wedding she spoke to TMZ, claiming Markle had reached out to her and the rest of her family members askign them to stay out of the headlines until after wedding.
"She's not gonna tell me that I can't speak about my own life or my father's, where it's a matter of public self defense," Samantha said. "The media is disparaging us. I'm not gonna take it. She's not qualified to suggest that I don't. Under any law in this country."
"This is not Great Britain. I am a United States citizen," she continued. "That's all there is to it. She's way out of her league to tell me that I can't speak. I'm not saying anything about her life. I'm talking about my life or my father's. She has to respect it."
The harsh tweets continued days after the wedding, with her claiming the Markle family was "embarassed" by her.
Markle and Samantha are related by their father, Thomas Markle.
Photo: Getty Images/Mark Cuthbert