Tetra Pak heir Hans Kristian Rausing has pleaded guilty to a charge of preventing the lawful and decent burial of his wife's body.
Rausing also admitted driving a vehicle while unfit through drugs at the Isleworth Crown Court, in west London.
Police discovered the body of mother-of-four Eva Rausing in an advanced state of decomposition after they arrested her husband on suspicion of driving under the influence of alcohol or drugs on July 9.
A post-mortem examination established that she died on May 7 and had drugs in her system, including cocaine, the court heard.
Her decomposing body was found in a fly-filled room in their luxury London home hidden under a pile of clothing and bin bags which had been taped together.
The court heard that Rausing told police in a statement after his arrest: "I do not have a very coherent recollection of the events leading up to and since Eva's death. Safe to assure you that I have never wished her or done her any harm."
Rausing's statement continued: "I did not supply her with drugs.
"I have been very traumatised since her death. I do not know what caused her death. I did not feel able to confront the reality of her death.
"I do not feel, with the benefit of hindsight, that following her death I acted rationally.
"I tried to carry on as if her death had not happened and batted away any inquiries about her."
He added: "I believe, in the period since Eva died, I have suffered some form of breakdown."
Mrs Rausing and her husband faced drugs charges in 2008 Mrs Rausing, 48, one of Britain's richest women, was found beside a bed in an annexe on the second floor of the opulent house in Cadogan Place in Chelsea, which she shared with her 49-year-old husband.
Bearded and bespectacled, Rausing, whose family made a fortune when they sold the Tetra Pak drinks carton business in the 1990s, has been on bail since his arrest.
Bail was granted on condition that he reside at the Capio Nightingale Hospital, a private hospital in London, and only leave the building accompanied by a member of staff.
Both Rausing and his wife had a long history of drug abuse.
In 2008 the couple were in trouble with the police over drugs but the prosecution was formally discontinued.
Hans Rausing, then 45, was charged with drugs offences after police found crack cocaine, cocaine and heroin during a search of his home.
After lengthy discussions between his legal team and prosecutors, he accepted a conditional police caution instead.
Neither Hans Rausing nor his wife, who also faced drugs charges, was present at City of Westminster Magistrates Court that August to hear that the prosecution had ended.
The couple had been arrested in April 2008 after Mrs Rausing was caught with drugs as she tried to enter the US Embassy in London.
