Meghan's half-sister Samantha Markle blasted her pregnant sibling and told her depression was no excuse for her behaviour.
During an explosive interview with Oprah, the Duchess of Sussex spoke bravely about struggling with suicidal thoughts.
Her dark thoughts stemmed from the mounting pressure of her Royal duties before she stepped down with her husband Prince Harry.
Yet her half-sister, on father Thomas' side, had no sympathy for Meghan and blasted the former Suits actress in an extraordinary attack.
In a cutting response, Samantha claimed mental health wasn't an excuse for treating people "like dishrags".
She told Inside Edition: "Depression is not an excuse for treating people like dishrags and disposing of them."
Her scathing dig was a direct response to tearful Meghan expressing her feelings in the TV interview.
Meghan told Oprah: "I didn't want to be alive any more -this was a very real and frightening constant thought."
Recently, Samantha released her tell-all book The Diary of Princess Pushy’s Sister Part 1.
But Meghan said she hadn't seen her sister in nearly two decades and rubbished claims she knew anything about her in her bombshell interview detailing all about her new life across the pond.
"I think it would be very tell all when you don't know me. I grew up as an only child." She said.
"The last time I saw her, 18 or 19 years ago and before that, 10 years before that."
Samantha hit back claiming "how can she not know me?" when she said they have photographs together.
She said: "I don't know how she can say I don't know her and she was only child. We've got photographs over a lifespan so how can she not know me?"
In another blow, Meghan told Oprah her sister only changed her name from Grant to Markle when she began dating Prince Harry.
But Samantha said: "I was a Markle before her. Markle has always been my name."
Meghan and Prince Harry have built a life for themselves in Los Angeles with their son Archie.
The couple has also revealed that they are having a baby girl.