Looking for story re dead wife helping with trick or treaters

[TheAmbidextrousLeftHander]

What I can recall:

• A married couple entertain some trick or treaters with a story
• After the trick or treaters leave, the wife relays her regret to her husband
• Apparently he killed her and her lover- burying them at the back of the garden
• Her spirit is able to ?become corporeal and interact one day a year - ?Halloween
• The lover can too, but refuses, sulking in his grave
• - she expresses her regret and returns to the back of the garden, fading as dawn breaks
• The husband reflects

This was The Ambidextrous Lefthander