Hi Thalassa -- I uploaded corrected file to fix the title display.
As to the Preface by Henry James, I did not find it to be a spoiler --- he comments about his writing intentions and how he feels about the mood of the story and the characters, and responds to some criticisms, and so on. Not really any discussion of plot. So I guess it will be up to you. (I personally almost always read prefaces AFTER I read the story
. )