Prince Harry's Horror! Girlfriend Meghan Markle's Own Family SLAMS Actress In Scathing Rant

Prince Harry's new romance is already doomed! The royal's girlfriend Meghan Markle's bitter family has threatened to tear the new pair apart, RadarOnline.com can exclusively reveal.

The sister of 35-year-old Suits actress — and possible future princess — confirmed the secret relationship to RadarOnline.com, but warned that the Prince, 32, could break things off when she reveals her bombshell story.

Samantha Grant claimed to have raised Meghan for 12 years growing up in California, boasting a family album of childhood pictures as proof.

Now wheelchair-bound and living in Florida, Grant, 51, accused Markle of not being the humanitarian she makes herself out to be.

"The royal family would be appalled by what she's done to her own family," Grant told RadarOnline.com. "The truth would kill her relationship with Prince Harry, he wouldn't want to date her anymore because it puts her in a bad public light."

"I certainly don't think Harry or his family would want to associate with her afterwards," slammed Grant, a successful writer in the arts industry.

Markle and Grant's father Tom — who filed for bankruptcy in June — and his older daughter are hurt by the superstar's lack of emotional and financial support, sources said.

Another source close to Meghan told RadarOnline.com she's overwhelmed with the media frenzy, and her phone has been ringing off the hook with friends and co-stars desperate to know more about the secret relationship.

"Meghan's been glued to her phone since she found out the relationship was going public on Sunday. Her WhatsApp notifications are never-ending and her social media has exploded," an insider told RadarOnline.com.

"She's barely sleeping. Meghan was awake all night on Sunday and only slept an hour or two on Monday. The truth is she feels guilty even though it's not her fault, she's desperate for the relationship to work."

Insiders said Harry, one of the world's most eligible bachelors, is "besotted" with the actress after meeting her this spring in Toronto.

The Prince was promoting the Invictus Games for disabled servicemen, while Markle has lived in the Canadian city for several years.