Actress Julia Roberts from the film 'August: Osage County' arrives at the 20th annual Screen Actors Guild Awards in Los Angeles, California on January 18, 2014. Photo: Lucy Nicholson

JULIA ROBERTS was said to be devastated on Tuesday night after her half-sister was found dead from a suspected drug overdose only three weeks after making an extraordinary attack on the star.

Nancy Motes had vented her fury at her Oscar-nominated sister in a series of Twitter messages, writing in one: “America’s Sweetheart is a B*** H!!”

The 37-year-old also claimed she had suffered years of torment over her weight from her famous older sibling, whose films include America’s Sweethearts, Pretty Woman and Notting Hill.

Miss Motes, a production assistant on US drama series Glee who had battled obesity and depression, was found dead in the bath by her fiance on Sunday. He discovered her body at a house in Los Angeles where she had been pet sitting. Prescription drugs were found at the scene.

Miss Roberts, 46, who is nominated for the best supporting actress Oscar for the drama August: Osage County – about a warring family – did not attend a lunch with fellow Academy Award hopefuls on Monday and cancelled a TV appearance.

In the weeks before her death, Miss Motes” rocky relationship with Miss Roberts had apparently soured even more.

On January 19 she tweeted: “So my ‘sister” said that with all her friends & fans she doesn’t need anymore love. Just so you all know “America’s Sweetheart” is a B*** H!!”

She continued : “Do you want to be a fan of someone so cruel? She’s not even that good of an actress. Happy you totally f***ed with me?” And she added: “I must admit I maybe going to far… But I never been so angry in my life. I”m actually a pretty easygoing, peaceful person.”

Three days later, on January 22, she tweeted that her family had “abandoned” her. In another cryptic message, clearly aimed at someone close to her, Miss Motes wrote: “Hey Hag! Glad you f***ed with me yet? You”re to LOVE what’s coming! FYI-You”re an awful, hate filled old pathetic excuse for a human.

“I must be grateful & not hateful. I must forgive. But Damn that is a REALLY hard thing to do sometimes, right?!?!”

Miss Motes – half-sister to actor Eric Roberts and actress Lisa Roberts Gillan and aunt to Emma Roberts, star of the US series American Horror Story – had a £20,000 gastric bypass in 2012 after her weight rose to more than 21 stone.

In an interview last summer she claimed she was “incredibly hurt and very sad” at remarks Miss Roberts allegedly made about her waistline.

“When you”re in a family of very, very exceptionally beautiful people, it’s intimidating,” she said. “Growing up as Pretty Woman’s little sister has definitely made me try to see the person inside and not the person outside. A lot of my life I felt judged for my weight.”

She claimed Miss Roberts had not been supportive, saying: “When I was in high school and she was an adult, she would just let me know that I was “definitely overweight”. She would make it quite clear to me and in a not so nice manner.”

After Miss Motes left school in Smyrna, Georgia, she followed her sister to Hollywood in 1995 with dreams of becoming a star herself. But she claimed Miss Roberts – who has the same mother, Betty Lou, but a different father – “did not want to see me go down that path, mostly because I was overweight. My weight has fluctuated my entire life. So I just got a lot of criticism from Julia, which was very discouraging for me.”

And she said that while Miss Roberts was feted in Hollywood for her breakthrough role as a prostitute in Pretty Woman in 1990, Miss Motes, then 13, was bullied and made fun of because her sister was playing a vice girl.

She said her sister’s jibes continued after she moved to Los Angeles three years ago, with the actress allegedly making a cruel remark about her weight as she struggled to unpack. “I said, ‘F*** you’. I had a pinch from sitting in the car for such a long time, I don’t think it was much to do with my weight. She was rude and I was rude, and we cooled off,” said Miss Motes.

A few weeks later she suspected she saw Miss Roberts gossiping about her size at her birthday party.

Suffering from depression, Miss Motes gorged on burgers and milkshakes, before seeking surgery in an attempt to slim.

In the interview, she described her relationship with her sister as “a work in progress” and said she was unsure if Miss Roberts would attend her wedding to film locations manager John Dilbeck this May. “It’s not going to be fixed overnight, nor do I think it’s going to be fixed at this point by me just getting skinny,” she added.

She then insisted: “My family love each other fiercely, we”re really not different from any other family. I love Julia absolutely, and I have no doubt she loves me.” But she also added: “I want to be known as more than Julia Roberts' fat little sister.”

Miss Roberts, who won the best actress Oscar for the film Erin Brockovich in 2000, is married to cameraman Danny Moder and the couple have three children.

Last October, Miss Motes tweeted: “It’s a shame when you get more support from strangers than you do from your family. I can’t wait to officially belong to another family! A family that loves & accepts me. Doesn’t throw shade my way. Forgives me for my mistakes & loves me for who I am.”

In December, she sounded depressed, writing: “Must remember to stay strong. Life is a fight. You have to stay in it.”

No suicide note was found but police said no foul play was suspected. A spokesman for the LA coroner said: “There were prescription and non-prescription drugs found at the scene. The role the drugs may or may not have played is not yet known.”

In a statement, her family confirmed she was “found dead of an apparent drug overdose” and said they were ‘shocked and devastated”.

Miss Roberts' New York-based publicist Marcy Engelman was unavailable for comment. - Daily Mail