When the author includes the quote, "when she abandoned herself a little whispered word escaped her parted lips. she said it over and over under her breath: "free, free, free! " she is showing that

Mrs Mallard is beginning to recognise and accept the positive that emerges from her husband’s death, being her newfound freedom. Tentative words such as ‘little’, ‘whispered’ and ‘breath’ convey her disbelief but could also reveal the moral conflict within the realisation to the reader. The repetition of ‘free’ is singsong-like as if to portray a vital moment of self-actualisation.

You could also analyse the contrast in ‘little whispered’ and the way she uses exclamation points in ‘free!’, etc

Not sure how detailed I was meant to go. Hope this helps hey x