Jessie and the other kids **spoilers**

I'm a huge Hitchcock fan and have seen most of his films, but tonight I watched "Marnie" for the first time. I can't decide if I liked it or not because I wasn't really prepared for it to be as disturbing as it was. I had heard it was about a beautiful woman who was a kleptomaniac, so I was expecting more of a crime caper than a dark psychological story.

Anyway, one thing that I don't quite get is the dynamic of Marnie's relationship with the little neighbor girl Jessie. It's clear that there is tension and animosity between them as soon as Jessie opens the door. I get that Marnie is jealous that her mother shows Jessie the caring and affection that Marnie desperately wanted from her, but I don't get Jessie's demeanor. Why would a neighbor kid be sassy to the adult daughter of the woman who is babysitting you? It was weird how Jessie almost taunted Marnie about how the mother is baking HER a pie, loves to brush HER hair, etc. And the other girls playing outside seemed to stare at Marnie like she was a pariah. Why? Nobody knew her "secret."

Also, are we to assume that after "the incident" Marnie and her mother moved to a new place where nobody knew them and started new lives, or that they still lived in the same place and everybody knew the mother's version of what happened?