How do you interpret Mrs Drover's psychological state?

Londoners faced terror and devastation from the Blitz.  For weeks straight and over a period of years, bombs were dropped by German planes over London.  Many people fled to the countryside.  The constant fear of hearing air raid sirens and low planes flying overhead caused psychological damage in some people.  People developed anxieties.
Mrs. Drover and her family left their London home because of the Blitz.  She returned one day to her abandoned house to fetch a few items.  Once there, she found a strange letter.  It was supposedly from her former lover, a man who was presumed dead long ago.  He had been an ominous fellow.  He had cut her hand many years before, and she still bore the scar.  Mrs. Drover

instinctively looked for the weal left by the button on the palm of her hand ("The Demon Lover").

In the letter, her former lover promised to meet Mrs. Drover on that day, and she dreaded such a meeting.  She quickly left her house.  She found a taxi cab and got into it.  It began to drive and then stopped.  She saw the driver:

Mrs. Drover's mouth hung open for some seconds before she could issue her first scream.  After that she continued to scream freely and to beat with her gloved hands on the glass all round as the taxi, accelerating without mercy, made off with her into the hinterland of deserted streets.

The writer does not clearly state whether Mrs. Drover was indeed held captive in the taxi cab by her former lover, or if it was all in her mind.  The traumatizing effects of the Blitz may have caused her to enter an altered psychological state.  This state may have led her to imagine the encounter with her former lover.