Want the best of The Telegraph direct to your email and WhatsApp? Sign up to our free twice-daily Front Page newsletter and new audio briefings. “It feels like a horrible dream to me that I wish I could just wake up from.“I am suffering every day thinking of you and what happened to you and I wish I could turn the clock back on what happened and you could still be alive today.“Sophie I wish things could have been different and that you rest in peace with a God.” The patio where Sophie Lionnet’s body was foundCredit:Metropolitan Police Sophie Lionnet was imprisoned and tortured to deathCredit:Metropolitan Police/PA In a letter read out to the London court, Kouider wrote: “Dear Sophie, May peace be with you. First of all I wish everyone especially her parents and family well, all are suffering.“How deeply sorry I am for what happened and in fact we shared many good times.“Sophie I am shocked and sad that you are not part of this world any more. Ouissem Medouni and Sabrina Kouider in a court sketchCredit:Elizabeth Cook/PA When Miss Lionnet’s body was discovered in September last year, firefighters were convinced it was that of a small child because she was so emaciated after weeks of starvation. She had five fractured ribs and a cracked breast bone.Kouider had become obsessed with Mr Walton after a “very turbulent” two-year relationship which ended around 2013. She embarked on a campaign to ruin him before becoming paranoid that her “shy and timid” nanny was conspiring with him.In a psychotic condition known as a “folie à deux” – or “madness of two”, Kouider and Medouni, a former banker, began to reinforce each other’s fantasy world. They were found guilty of her murder following a trial. Sophie Lionnet’s mother, Catherine Devallonne (right), and father, Patrick Lionnet (left) arrive at the Old Bailey on TuesdayCredit:Nick Ansell /PA Sophie Lionnet was thin and gaunt in this picture two days before she was found deadCredit:Metropolitan Police Jailing them for life, Judge Nicholas Hilliard QC said the murderers had created a “complete fiction” about Miss Lionnet, whom they tortured in her final hours to make a “confession” about working with Mr Walton to undermine them. A woman who tortured and murdered her nanny before burning her body has written a bizarre letter to her saying she is shocked she is dead.Sabrina Kouider wrote the letter from prison in which she apologised for killing au pair, Sophie Lionnet, adding that she wished she could “turn back the clock”.However, a judge at the Old Bailey yesterday rejected her claims of remorse and jailed Kouider and her partner, Ouissem Medouni, for a minimum of 30 years each.The court heard that Kouider, a 35-year-old fashion designer, suffered from a psychotic disorder and convinced her infatuated 40-year-old lover that their nanny was plotting with Mark Walton, a founder of the band Boyzone, to destroy them.Miss Lionnet, 21, suffered waterboarding, beatings and her body was dumped on a bonfire before her killers prepared a barbecue at their home in Wimbledon, South-west London. The victim’s father, Patrick Lionnet, said what the couple did to his shy and reserved daughter was “beyond comprehension” and “unforgivable”.In a letter addressed “dear Sophie”, Kouider acknowledged the suffering of her victim and her family, saying how “deeply sorry I am about what happened to Sophie”. He said her behaviour towards the victim was “entirely driven by Ms Kouider’s mental illness in her desperation to obtain evidence of Mr Walton’s abuse”.By the time of Miss Lionnet’s death, it was Medouni who had taken over the “dominant role” in her interrogations, the lawyer argued.But Orlando Pownall QC, said Kouider was the “dominant” party who preyed on the “weak”, including his client Medouni.He said the former banker had been “indoctrinated” by a woman with the capacity for “sudden and extreme violence”.”Such was the all consuming nature of his commitment to Sabrina he did not have that many friends at all.” He told them: “I’m sure on all the evidence you were both involved in torturing Sophie in the bath in the lead-up to her death in making her think she would drown unless you gave her information you wanted which was not in her power to give because it did not exist.“The suffering and the torture you put her through before her death was prolonged and without pity.”He added that Kouider was motivated by an unjustified desire to make Miss Lionnet and Mr Walton “suffer”.The defendants showed no reaction in the dock as they were sentenced.Following their convictions, Miss Lionnet’s tearful mother, Catherine Devallonne, said: “These self-obsessed individuals who murdered Sophie did not believe Sophie had a value.”Those monsters repeatedly beat Sophie. They starved, tortured and broke her until she could no longer fight. They took away her dignity and finally her life painfully ebbed away until Sophie struggled to take her final terrified breath in the bath.” She wrote they shared some “good times” until “things went terribly wrong”.”I am shocked and sad you are not part of this world anymore. I’m suffering every day thinking of you and what happened to you that dreadful night. I only wish I could turn the clock back, it never happened and you would be alive with us today,” Kouider wrote.In mitigation, Icah Peart QC said the fashion designer’s delusional disorder coupled with an emotionally unstable personality disorder had caused her “irrational and completely overwhelming fear” that Miss Lionnet had been recruited by Mr Walton.