A woman who successfully set up her brother with one of her best friends ended up becoming so jealous of their relationship she tried to wreck their marriage. Husband and wife David and Sandra Greatrex, 53 and 52, from Plymouth, have told their shocking story of harassment, which culminated in David's sister Anne cancelling the couple's wedding using a fake email address just weeks before the big day. The couple have spoken about their family feud on Channel 5 documentary, Family Secrets and Lies, which airs tonight. Scroll down for video . David, 53, and wife Sandra, 52, from Plymouth, were harassmed by David's sister . 'I was in tears and was so angry. I did not think someone was capable of doing that,' says Sandra of the horrifying moment Anne informed them she'd managed to cancel their nuptials behind their back. 'Everything was paid for so it was a lot of worry,' she added. Luckily, the couple managed to piece their  plans back together in time for their winter wedding though. and they subsequently took Anne to court for harassment. Sandra first met David after his 20-year marriage fell apart and her friend Anne, David's sister, suggested they meet. 'I met Anne for coffee and David came out and I've never let his side since,' she says. 'When I first met him I didn’t realise how important he would become. He’s my everything.' Before long the couple were inseparable. But although Anne's matchmaking had worked, she was not happy about their relationship and started sending Sandra threatening text messages telling her to stop seeing her brother. 'They were hurtful at the time but I couldn’t understand why. Maybe it was jealousy,' says Sandra. ‘My mum had lung cancer and was going through chemo at the time. Anne was sending messages saying, "Your mum’s dying and you better get back to her".' Ann Duffy, pretended to be her now sister-in-law and cancelled her brother's wedding . But the relationship continued and Sandra and David became even closer. Then one day Sandra proposed. 'I was joking around - but not,' says Sandra. Then David took the hint and gave Sandra a romantic proposal. For a while the angry texts from Anne tailed off. 'We went to the registry office, put the deposit down and made special invites - I couldn't believe it was really happening,' Sandra says of the wedding. 'My mum got involved in the beginning and helped me pick my dress.' But in 2012, Sandra’s mother lost her battle with cancer and a year later David’s mother Celia also became ill and moved in with Sandra and David. But Sandra wouldn’t let Anne in their house, which reignited the rift. ‘I wouldn’t let her come to my house and see her mum because of all the hurtful thing she’s said to me. 'She could come to take her out but not in the house. 'She made a big deal about that and said that I was trying to replace my mum with her mum and that I was taking her away from her.' Then 20 days before the wedding, the couple received a distressing phone call. David remembers: 'I was lying in bed when the phone rang and Anne said: "I've got to tell you - you might want to pot the phone on loudspeaker." 'Then she said: "I’ve saved you from divorce. I've cancelled your wedding."' David and Sandra Greatrex at their wedding . Sandra says: 'I was in tears and angry. I wanted to go nuts at her. Everything was paid for so it was a lot of worry. We were up all night. 'I did not think someone was capable of doing that. 'How low can you get? This is your brother getting married. We had paid for everything and I thought she’d ruined it. 'In the morning we rang the registry office and they confirmed that our wedding had been cancelled. 'They said we should come in so they could print everything off for us to give to the police.' Anne had created an email address in Sandra's name to set about jeopardising the couple's plans. Luckily the registry office juggled things around and were able to  fit David and Sandra back in on their planned date. Ann Duffy called Plymouth Register Office 20 days before her brother's wedding and canceled it . Anne was jailed for eight weeks at Plymouth Magistrates' Court. When Sandra reported Anne to the police, Anne admitted it straight away and was given a date to appear in court. But the angry text messages still continued and when the big day arrived, the couple still feared Anne might ruin it. Sandra and David at their wedding . 'We didn’t see her until we got out side,' remembers Sandra of their wedding day. 'We were going to get photos taken when she started shouting commiserations, filming me and putting two fingers up. 'I wish I didn’t have to go through that, but I still had the best day I could have wished for.' At court, Anne pleaded guilty to harassment and was sent to prison. She was jailed for eight weeks at Plymouth Magistrates' Court and was also given a restraining order against Sandra for an indefinite period. David said: 'It was quite upsetting. She got eight weeks but I believe she only did four.' And of Anne's injunction against coming near Sandra, David says: 'It's the best way – the less we see of her the better.' Sandra says: 'It's jealousy bitterness and anger. To this day if she could split us up she would. 'But we’ve been through so much, I don’t think there’s anything out there that could hurt us.' Anne did not want to appear on the programme but said she had her reasons for cancelling the wedding and loved her brother. Family Secrets & Lies is on Channel 5 tonight at 10pm .
Sandra and David Greatrex were introduced by David's sister, Anne Duffy . Soon Anne started sending threatening text messages  to Sandra . Rift got so bad she stopped tried to cancel their wedding using fake email .