Julia Roberts tried to get her half-sister to go to rehab in the months before her death.
Roberts had a "complex" relationship with her half sister Nancy Motes that was reportedly made worse by the former production worker's addiction, and Nancy's public attacks on her famous relative which were often triggered by the actress' pleas for her to seek help.
A source told RadarOnline "The sisters had a very complex relationship. They used to be very close when they were younger. Julia tried in vain over the years, even in the last six months, to get Nancy to go to rehab. Nancy refused the offers and that is when she would often publicly lash out at Julia.
"It hurt Julia, but she knew her sister was battling addiction.
"The addiction to prescription drugs made Nancy a totally different person. There would be periods of sobriety and with that brought clarity. It would be during those moments that the sisters would reconnect. Sadly, of course, those times became less frequent before her death."
The 46-year-old actress arranged for Nancy - the daughter of Julia's mother, Betty Lou, and stepfather, Michael Motes - to check into rehab last year, but she "backed out" shortly before she was due to enter the facility.
The source added: "She had agreed to go... this was about a year ago.
"At the last minute, Nancy backed out, gave no reason. Yet, Julia told Nancy if she was ready to get healthy, all she had to do was call. Julia never got that call.
"Julia is taking the death very hard. It's extremely difficult for her because it didn't have to happen. Julia has a great support network around her and she is relying on her husband [Danny Moder], more now than ever."
It has been reported that Nancy left a "ranting" suicide note in which she blamed Julia for her problems.
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