"Downton Abbey star Amy Nuttall has reportedly been left heartbroken after husband Andrew Buchan 'walked out' on her and moved in with new co-star Leila Farzad after meeting the glamorous actress while working on BBC series Better, The Sun reports. The reports come just weeks after Leila shared a gushing Instagram post paying tribute to Andrew for 'holding her up and wiping away her tears,' alongside a snap of them filming the drama. A source told the outlet: 'It was a huge shock. Amy is heartbroken.' Andrew is said to have told Amy their marriage was over before Christmas, leaving the actress devastated and their friends in a state of shock. The source added: 'For Andrew to walk away from his family was a huge shock to us all – and Amy is heartbroken. Everyone who knows them thought they were going to be together forever. 'But he's packed his bags and left with his new co-star. Whatever has gone on, it seems to have been enough for him to re-evaluate his whole life and rip up their marriage. 'Nobody is quite sure of the exact details, but Andrew has clearly had his head turned pretty dramatically.' Andrew plays a well-connected criminal alongside Leila's corrupt police officer in new crime drama Better, which launched on BBC One in February. The London born, Oxford-educated Leila has previously taken roles in Law & Order: UK, Man Down, This Time With Alan Partridge and I Hate Suzie - a part that earned her a BAFTA TV nomination."