Meghan Markle's Sister Calls Her Narcissist for 'Lost Her Dad' Claim to Oprah

Meghan Markle's sister is furious the Duchess essentially disavowed her family -- especially their dad -- during the Oprah interview, and claims she's merely playing victim for sympathy.

Samantha Markle went HAM Monday while on the Australian radio show "Fifi, Fev & Nick" ... calling BS on Meghan telling Oprah she'd lost her father because of Royal family pressures.

Samantha said, "When she said 'I lost my dad' -- the world watched as my dad was in interviews wanting communication with his daughter. She didn't lose her dad. She iced her dad!"

Samantha didn't pull punches, as she played dime-store psychologist on Meghan, saying ... "I see a narcissistic personality disorder," and suggested Meghan needs counseling.

It gets worse ... she also equated Prince Harry to a kidnapping victim who's falling in love with his captor. Samantha said, “I feel sorry for Harry. He fell victim to her negligence, and I will say sociopathy ... she pulled him away from his family, all of his friends, the life that he knew."

As for Meghan's claim to Oprah that she didn't know anything about the Royals and their way of life -- Samantha claims Meghan studied the UK Monarchy, and even tries to emulate Princess Diana.

Samantha added, she doesn't think Meghan's embarrassed of her family -- she just didn't want them around to expose lies Samantha claims her sister's told.