joseph o'riordan , 73 , stabbed 47-year-old wife of eight times after he discovered she had been having an affair with a postman .
she was a councillor at the time , rang an ambulance after the attack in october last year and admitted what he had done during the 999 call .
emerged that four months later , while on remand , o'riordan wrote to his wife from jail asking her to get my things together ' before for his trial .