The jealous one - Celia Fremlin

The Jealous One (1964), Celia Fremlin's fifth novel, opens on its protagonist Rosamund as she wakes from a mid-morning nap to find, to her delight, that she is running a temperature.
Surely that explains her blinding headache, and even the weird, delirious dream in which she had murdered her overly seductive neighbour, Lindy? A great relief, then, to find this was merely the work of a fevered imagination. Until her husband exclaims, 'Rosamund! Have you any idea what's happened to Lindy? She's disappeared!...'

'A tense situation, ultimately resolved by a beautifully fitting
plot-twist. Even more memorable than the suspense story is the witty and
acute comedy.' New York Times

'A brilliant example of the
psychological thriller. The little worm of jealousy devours its way into
the mind, gradually, page by page.' Hampstead & Highgate Express