The wealthy music mogul supported her financially through the highs and lows of his successful career. After leaving Boyzone, he found success with Fifth Avenue and more recently as a judge on Vietnam Pop Idol. The musician said they lived together for two years in Queensway, London, before she disappeared and they split up. After Mr Walton stopped paying her rent in 2014 when they split, she took out a non-molestation order claiming harassment, the court heard.She also rang his mother in Dublin, contacted his business partners and created a fake Facebook page accusing him of being a “paedophile”, he said.Mr Walton told jurors: “I was broken, emotionally broken but I loved her.”The court has heard there is no truth in any of the accusations against him. Kouider and Medouni have admitted perverting the course of justice but deny murder.The trial continues. Sabrina Kouider was described by former boyfriend Mark Walton as someone who ‘would go crazy over something trivial’ He said Kouider had been “abusive” and “exhibited a manipulative and controlling nature” with a “calculating streak”. He also described her as a “really gentle, sweet, loving” person who could become “quite scary” in seconds.He told jurors: “Sabrina shared some stories from her past.”I guess knowing that, I felt it brought us closer together at times, but it was turbulent, probably the most turbulent relationship I had ever been in.”She would go from softly spoken French accent then she would flip, get very angry, very loud and just not care where we were. She would just go crazy over something trivial.” The founder of boy band Boyzone has revealed in court the “turbulent relationship” he had with his ex-girlfriend who is accused of murdering her French nanny.Mark Walton, who created the Irish boy band in 1993, flew in from Los Angeles to give evidence at the Old Bailey trial of fashion designer Sabrina Kouider.The 35-year-old mother and her partner Ouissem Medouni, 40, are accused of murdering au pair Sophie Lionnet and throwing her body on a bonfire at their home in Wimbledon, south west London.The couple had allegedly tortured the shy 21-year-old into “confessing” to being in league with Mr Walton.However, Mr Walton said the first he knew of Miss Lionnet was when murder squad detectives contacted him in September last year. Ouissem Medouni (left), 40, and his partner Sabrina Kouider, 34, appearing at the Old Bailey in LondonCredit:Elizabeth Cook/PA Miss Lionnet, 21, was later allegedly beaten, killed and thrown on a bonfire by her employers Kouider and Ouissem Medouni The softly-spoken Irishman said he met Kouider in a NatWest bank in Notting Hill in 2011 and hit it off straight away.He said: “I was in love. She was my life then so…”He said he gave her thousands of pounds a month, paid for nannies and even covered £12,800 in rent after she had left him, the court heard. Yet Kouider then fired her nannies, and accused them of stealing or being attracted to her “friendly” boyfriend, it was alleged. 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.