The bodies of Jonathan and Derisa Trenchard were found at their home in Carbis Bay, Cornwall, in October.
An inquest in Truro heard Trenchard, 50, thought his wife was having an affair despite there being no evidence.
Coroner Dr Emma Carlyon ruled Mrs Trenchard, 48, was unlawfully killed by her husband.
The inquest previously heard the pair were devoted to their three sons and had a seemingly happy marriage.
But Mr Trenchard had become paranoid and needed constant reassurance about their relationship, the coroner was told.
Devon and Cornwall Police gave evidence that checks by officers on the couple's computers and mobile phones did not reveal any evidence that Mrs Trenchard was seeing anyone else.
Despite his fears, the couple, who had been married for 24 years and had moved to Cornwall from Reading, had recently booked a holiday in order to renew their marriage vows for their 25th anniversary.
However, the inquest heard Trenchard had been receiving counselling through his GP for depression and irrational thoughts.
He was receiving medication for anxiety but refused to be referred to a mental health team.
A family friend also gave evidence, saying Trenchard had a troubled childhood. His mother had had mental health problems and he left home after falling out with his father, living with another family.
Police officers concluded it was clear Trenchard killed his wife using a hammer before stabbing himself in the chest.
Pathologist Dr Amanda Jeffery told the inquest the scene "was consistent with the murder of Derisa by her husband and then the suicide of Mr Trenchard" and she did "not believe it to be a suicide pact."
A woman was beaten to death with a hammer by her husband before he stabbed himself with a kitchen knife, a coroner has ruled.