Could anyone help me find the following French film: appears to be made in the 1970s, is in color, is about a girl (and younger sister) who spends the summer in the south of france with her mother while her father is to arrive later.  The girl is about 12-14 and the film occasionally voices over her diary entries.

Key scenes:
 -early scene has girl entering a room just after an argument between the father and mother
 -mother has an affair with a young artists who is moving to New York and wants her to go with him
 -seeing the mother's newly bought car on arrival, the father smashes it into a tree.
 -in the south of france, the mother & father have another argument, the father is voilently grabbing her, calls her a whore, etc., and being distressed over this, the girl breaks a mirror, places a broken piece by her throat, and threatens to kill herself unless they stop

These are all the scenes I can remember (also the family is with their relatives, an uncle and aunt).  I didn't see the whole film so that's why I need someon's help.  I gave this to a film critic and he didn't even know!