Heather Key, who had been drinking cider all day, knifed Nicholas Stanley in the heart as he walked into the flat that he had helped her fiance find.
Mr Stanley, a graduate who worked as a housing support officer for the YMCA, was stabbed three days after Key's fiance, Melvyn Rees, moved into the flat in Mount Pleasant, Guildford, Surrey, James Curtis QC, for the prosecution, said. Key and Mr Rees - who met at an alcohol detoxification centre - had been drinking cider all day as they celebrated her birthday on 15 July last year. Mr Rees found himself locked out of the flat - and turned to Mr Stanley for help.
'It was a great misfortune that he arrived at the flat when she was in a mentally unstable condition induced by drink,' Mr Curtis said.
Key was remanded for reports after admitting manslaughter.