The British producer admits he's "furious" about comparisons made between the Clueless star's death and Haim's suspected overdose last week (10Mar10).
Speaking exclusively to U.S. news show Access Hollywood, Monjack says, "That's absurd... Corey was someone that had openly used drugs for many, many years and had a problem. Brittany was someone that had never used a drug in her life."
Asked if he ever saw Murphy take drugs, an angry Monjack scowled, "Absolutely not and nor did anyone else."
Medications were found in the actress' system at the time of her death, but her 20 December (09) death has been ruled an accident following an autopsy.
Brit Simon Monjack and Murphy were dogged by odd couple remarks when they wed in 2007, but both maintained that they were very much in love.
Now, following the star's death in December (09), the producer/photographer has gone public with the truth behind his romance with the actress.
He admits his visa was expiring when he started dating Murphy but insists that had nothing to do with the couple's decision to wed.
He tells U.S. news show Access Hollywood, "My visa was expiring and I would have had to go... (but) I mean Brittany Murphy marrying for a visa is so crazy."
And Monjack accepts his romance with Murphy may have been unorthodox to some - but he was smitten with her and she with him.
He adds, "It was more of just an attraction to the person... She just fell in love."
The producer, who is eight years older than Murphy, also reveals he first fell for the actress when she was a teenager - but had to wait for her to grow up: "She was, like, very young when she was 17... It would have been like dating a 12 year old."
The actress died in December (09) after suffering a cardiac arrest at her Hollywood Hills home, and her grieving husband subsequently set up the Brittany Murphy Foundation in her honour.
He even planned a charity gala for the launch of the Foundation last month (Feb10), charging $1,000 (£625) a ticket, but cancelled the bash at the last minute.
It was later revealed the foundation was not legally registered as a charity with the state of California, and a statement was issued through the organisation's website revealing all donations would be handed back until non-profit status is approved.
Monjack tells TMZ.com he has started the process of handing back all the money the organisation received, but reveals it only totalled $800 (£500). He insists plans to resurrect the foundation are going ahead and he is taking the "the proper steps" to make sure the organisation is registered.
The 32 year old suffered a fatal cardiac arrest in her palatial Hollywood Hills home in December (09).
The star's mother Sharon and widower Simon Monjack are struggling to cope with their grief over the actress' death and have decided to move to New York, the filmmaker tells TMZ.com.
Murphy bought the house from Britney Spears for just under $4 million (£2.5 million) in 2003.
It has also been confirmed that Monjack was left out of Murphy's will - she left her entire estate to her mother. The British director claims the star's will states: "I am married to Simon Monjack who I have intentionally left out of this will."
The 32-year-old actress passed away on 20 December (09) after suffering a cardiac arrest at her Hollywood Hills home.
Academy bosses have personally invited Monjack to the Oscars, so he can be in the audience when they pay tribute to Murphy among the stars who have passed away.
He tells EOnline.com, "I have been honoured by an invitation to the Academy Awards, which I am very grateful for. They will include Brittany in their In Memoriam tribute, along with some of the other gifted actors that died this year."
Monjack plans to take Murphy's grieving mum, Sharon, as his guest, but he fears she may not be well enough to attend the Oscars.
He adds, "I hope Sharon can attend, but her presence will be dictated by her health and that's a decision that will be made nearer the day. I only wish I were attending under different circumstances, but I know Brittany would want to be represented there."
The 32-year-old Clueless actress passed away on 20 December (09) after suffering a cardiac arrest at her Hollywood Hills home.
The tragedy was ruled accidental by officials at the Los Angeles County Coroner's Office earlier this month (Feb10), with pneumonia listed as the primary cause of death.
Anaemia and "multiple drug intoxication" were also stated as contributing factors, and officials released Murphy's toxicology report on Thursday (25Feb10), identifying all the drugs in her system.
The report stated the star had only been taking medications to treat what she believed was a bout of influenza and she had "no history of alcohol or drug abuse."
Monjack admits he couldn't hold back the tears when reading the report - but he's happy the documents prove his wife was not abusing illegal substances before her untimely death.
He tells US Weekly magazine, "(I) sobbed and sobbed (when I read the report). I haven't gotten out of bed yet.
"She never did anything that she was accused of! We never hid anything. And that's been the case with everything in our marriage.
"Our marriage was dogged by these ridiculous rumours. Brittany's life was dogged by ridiculous rumours, and the truth always wins out. I hope people have the sense to really understand that everything was beautiful and wonderful in our relationship and so pure."
Angelo Bertolotti was denied access to Murphy's gravesite last week (15Feb10) after arriving at Forest Lawn Memorial Park in the Hollywood Hills to pay his respects.
Staff reportedly told the actress' estranged father that only family members could visit Murphy's grave - and because his name wasn't on her death certificate, they couldn't allow him in.
Murphy's half-brother Jeff, has since spoken out about the snub, calling it "a travesty".
A cemetery spokesperson addressed the incident by telling reporters if "particular families leave special instructions," they abide by them, prompting speculation it was Monjack and the Clueless star's mother, Sharon, who asked for Bertolotti to be kept out.
But Monjack is adamant he and his mother-in-law did not arrange to alienate Bertolotti.
He tells EOnline.com, "Neither Sharon nor I have heard from Mr. Bertolotti in any capacity for many, many years."
The Clueless star's husband Simon Monjack created The Brittany Murphy Foundation in honour of the actress - who died of a cardiac arrest aged 32 - in a bid to raise funds for art education.
But TMZ.com reports that the foundation is in name only - as it has not legally registered as a charity with the state of California.
Following requests for comment by TMZ.com, the website was suspended on Friday (12Feb10) before going back online - carrying the additional message, "(The foundation) is a private foundation. And is currently awaiting its non-profit status.
"Until we have our non-profit status approved before proceeding to insure that we can truly honor Brittany's charitable desires... any donations made up until this point will be returned until we have all our paperwork solidified."
Monjack had planned a charity gala for the launch of the Foundation earlier this month (Feb10), charging $1,000 (£625) per individual and $10,000 (£6,250) for corporations to attend the event, but cancelled the bash at the last minute.
The Clueless star passed away on 20 December (09) after suffering a cardiac arrest at her Hollywood Hills home.
Her widower Simon Monjack admits the actress was heartbroken about the ongoing lull in her career, after her character was written out of Sylvester Stallone's upcoming blockbuster The Expendables.
The film would have marked Murphy's return to the big screen after years off to nurse her cancer-stricken mum.
Monjack tells U.S. talk show host Larry King, "(The public outpouring of support after her death) was unbelievable. And I think Brittany would have been more surprised than anybody. You know, her career, by her own admission, in the last few years - five or six - had taken a downturn."
Murphy's mum adds, "There was (a downturn) for probably the last maybe five years. I got really sick. You know, I had cancer twice. And she had initially taken off to be with me in the hospital and slept there every day for the four weeks, five weeks I was there and was just with me always and, you know, controlling all the doctors and making sure all the right things were done.
"I just never dreamed that (she would die first). You know, I always thought it would be me, not her."
Monjack admits Murphy believed she was being ostracised from Hollywood, adding: "It's funny, Brittany and I spoke about this often. And she had her theories - a rumour - the theory was that she had upset the wrong people at the wrong time.
"(But) she was the kindest, sweetest person. I think it was more that she was too kind, too sweet, too - she was this bubble that existed in a plane beyond ours."
The Los Angeles County Coroner's Office ruled earlier this week (04Feb10) the Clueless star's primary cause of death was pneumonia, with contributing factors of anaemia and "multiple drug intoxication".
Her husband Simon Monjack believed the 32 year old had contracted laryngitis, and he and Murphy's mum were nursing in their shared Hollywood Hills home, expecting her to make a full recovery.
But Monjack insists Murphy knew she was dying the morning she suffered a fatal cardiac arrest on 20 December (09) - and reached out to her mum to bid farewell.
He tells U.S. talk show host Larry King, "Her last days were full of the Academy (Award) screeners (DVDs), being in a soft, pink, fluffy Beverly Hills robe, mama coming and bringing soup and laying in - and laying on the sofa next to the bed.
"What happened that day (she died) was Brittany had laryngitis. I have no idea what to do with laryngitis. I'm a rabbi, not a doctor, so I pray instead of prescribe. So I asked Sharon to come down. We'd been talking, anyway, half the night... We were planning to move to New York, have a baby... We were talking about baby names.
"I asked Sharon to come down and Sharon came down. Brittany, for the first time, was almost fighting for air. Her eyes were not right. They were darting off left, right and center.
"That morning she woke up (and) she couldn't breathe. She went out to get some air. Sharon followed her out. I'll say this, because I know you (Sharon) can't. She said, 'Mom, I'm dying. I love you.'"
Murphy's mum Sharon adds, "From when she collapsed, I was with her in the bathroom. And I was sitting across from her with her little puppy, Clara. And she said, 'Mommy, please hug me.' And I went to get up and she just collapsed like right there."
Sharon Murphy and Monjack's comments were made in an interview before the L.A. Coroner declared the star's cause of death.