The tragedy made headlines. Her parents, David and Jackie Siegel, are wealthy resort magnates whose lavish lifestyle was captured in the 2012 documentary The Queen of Versailles, which chronicles their construction of the largest home in America.
Now, they hope to build a better future for teens with issues like Victoria's.
"One hundred percent of my focus right now is on saving lives. Not on business, not on houses, not on reality shows," David tells PEOPLE exclusively. "I want my daughter's legacy to be that thousands of lives will be saved because she lost hers. That's what's keeping us sane. We could have crawled into bed, pulled the covers over our head and been a basket case, but instead we embarked on this journey to help other people, to save other families from going through what we've gone through."
He and Jackie, 49, have started the Victoria's Voice Foundation to raise awareness about addiction. They believe young people are vastly over-medicated and under-educated about substance abuse. ("I was overactive when I was a kid. Fortunately, they didn't stick me on anything. But today, if a child is overactive, they stick them on Ritalin," David says.) They want high schools and colleges to mandate drug testing. And they want to grieve in a way that honors their child.
"By doing this, it's given us some strength, knowing that we're going to save other lives and that Victoria didn't die in vain," Jackie says. "That maybe death has a greater purpose."
Victoria's DeathVictoria was found dead in the Windermere, Florida, mansion the family calls home until Versailles is finished. The oldest of the Siegels' eight children, she suffered from anxiety, her parents say.
"Victoria was the perfect storm," David says of how her addiction began. "She had trouble getting through high school, she didn't like school, so she wasn't making good grades. She did graduate, but when she graduated, she didn't plan to go to college, at least not right away."
"She didn't know what to do," Jackie explains.
She began seeing a psychiatrist who prescribed her Xanax, and she "got hooked," David says. A family spokesperson has said it also helped her with her seizures.
Realizing she had a problem, Victoria confided in her mother a few months ago, saying she wanted to check herself into rehab. She was discharged too soon, the Siegels allege, and not given the tools and instructions she needed to cope with her addiction in the real world.
By June, she seemed to be doing better, insisting she didn't need to see a counselor because she was "fine."
"Obviously, she wasn't," Jackie says.
Courtesy Siegel family
Her parents remember her seeming "happy," excitedly going shopping to buy him gifts and flowers beforehand, writing him a love note and planning "something really special."
Then, the boyfriend's ex-girlfriend, with whom he has a child, went to visit him, the Siegels say.
"Three hours later, the ex-girlfriend sent her a text that was the most vile, horrible thing any girl in love could receive," David says. The alleged text, which the Siegels say was sent from the boyfriend's cell phone, was purportedly about how the former couple had reunited to have sex, and it claimed the boyfriend was using Victoria for her money.
Victoria's body was discovered that morning. The autopsy results, released Wednesday, show she died from acute methadone and sertraline toxicity. (Sertraline is commonly sold as the anti-depressant Zoloft.) The medical examiner ruled her death an accident, and her parents agree. She was so excited, Jackie says, to embark on the family's summer trip – a cruise to the Bahamas and journey throughout Europe – the following Monday.
"She wasn't depressed. She was very optimistic, and then the cyber text came and destroyed her," David says. "It was her first love. She was madly in love, and then the girl that sent it stabbed her in the heart."
Remembering VictoriaJackie had a particularly tough time mourning her daughter while in the spotlight after paparazzi snapped her taking photos of Victoria's coffin at the service June 9.
"It was just so traumatic. I was almost like a zombie. I didn't know if it was real or fake. One minute I'm crying uncontrollably, the next minute I'm just numb. And I'm trying to be strong for the kids," Jackie says. "But I wanted to remember every last precious moment of my daughter before she's down in the ground and going to be dirt. So I don't see anything wrong with taking a couple pictures."
Courtesy Siegel family
Still, the Siegels will always remember Victoria as she was during life: a beautiful, affectionate child who never gave her parents "any trouble" growing up.
"She was one of those people that always looked for the good in people," Jackie says. "She made some bad choices in friends, even though they were not a good influence on her, but she always gave them the benefit of the doubt."
"Whenever she saw me, she'd hug me, say she loved me," David adds. "The last time I saw her, we were standing in the kitchen doorway, and she hugged me, and I said, 'Wow, you're getting taller than me.' "
One of Victoria's rescued dogs, Zen, sat outside her bedroom door for weeks after her death, until he "realized she's never coming home," Jackie says. Now, the pup doesn't leave Jackie's side. "I guess he figures I'm the next best thing," she says, smiling a little. "Maybe I smell like her or something."
Courtesy Siegel family
Victoria's VoiceIf David could have one more moment with his daughter, "I think I would tell her that I'm sorry I wasn't a better father," he says, choking back tears. "I wish it was me instead of her."
But he's spent the seven weeks since her death educating himself about addiction, traveling across the country to meet with presidents of universities, sitting in on therapy sessions with addicts and talking with officials like the U.S. surgeon general and the head of the Drug Enforcement Administration.
"I think the fact that I am on this crusade, on this mission, has helped them get through this," David says of his family. "That we are going to make a difference, we are going to save lives, and I think that's helped my wife and I think it's helped the children. We're much closer than we were. Through adversity, you bond, and I think we've bonded. ... Everybody's sad. It's horrible what's happened. The most horrible thing that's ever happened in our life. But we're all hanging together, and they're all supporting me. I told them today, you guys are going to have to carry on the fight after I'm gone. I mean, at my stage in life I should be thinking about which beach should I go lay on and relax and enjoy the fruits of my labor. I'm starting a new career at a late stage in my life, but I'm determined that I'm going to make a difference."
The Victoria's Voice Foundation's goal is to bring together the thousands of small family foundations that spring up after someone dies from an overdose.
"People collect a little bit of money and they want to do good. They don't have a guide book, they don't have a playbook on what to do. They don't know how to raise money. So these little foundations, after a couple of months, just fade away. They're never heard of," David explains. "I want to get all these people instructions where I can have thousands of people out there all doing work in their communities, in their schools. This is going to take a village. I can't do it, a hundred people like me can't do it. It's going to take the people who have been affected by this. Everybody knows somebody that has lost a loved one to this."
Courtesy Siegel family
"Every school, every university or even high schools should have one course on drug addiction. The kids don't know what they're doing. They think that if a drug is prescribed by a doctor, it must be safe," he says. "They have no idea, these things, what they do, and we're way over-prescribing the drugs. But we've got to have courses in college, especially freshman year when they first come here. We've got to have random drug testing. That will save thousands of lives. Schools don't even know how to deal with this problem, so they look the other way. They pretend it doesn't exist, but it does."
The Centers for Disease Control and Prevention has classified prescription drug abuse as an epidemic. The statistics are staggering: In 2010, there were 8.76 million prescription medicine abusers in the United States, according to the National Institute on Drug Abuse. And the next year, 52 million people ages 12 and older had used prescription drugs non-medically at least once in their lives.
"It's a disease. If somebody gets cancer, you treat it," David says. "Well, if somebody starts doing drugs, you treat it. You can't just ignore it. It's not going to go away.
The Siegels are also encouraging people to participate in the Oct. 4 march in Washington, D.C., organized by UNITE to Face Addiction in Victoria's memory.
"My only regret is I wish I'd spent more time with her," David says. "You don't think they're only going to be there for a short time. You think, 'Oh, there's always tomorrow.' Well, there isn't always tomorrow."
For more information, visit victoriasiegelfoundation.org. For more on Jackie and David, watch Inside Edition when it airs Friday.