70’s/80’s YA Novel

Looking for a late ’70s–mid ’80s middle-grade/early YA novel — searching for a very specific summer story: • A girl stays with her grandmother over the summer in a small town. • There’s a housekeeper, and the housekeeper’s niece visits and ends up with the peanut-butter ice cream the girl loves. • The girl pretends to be asleep to avoid confronting Grandma—since she knows she’s in trouble—but Grandma later says something like, “I saw how you almost leapt out of bed…” • She has a summer friend, and after a fight the friend says, “My mother says you’re disturbed.” The girl doesn’t understand “disturbed,” and her grandmother explains it to her. • There’s a woman in the town who draws or paints her, and they have conversations where the girl doesn’t recognize the woman. • Eventually, it’s revealed this woman is her mother, who’d disappeared—most likely due to alcoholism or mental illness. • Later, her father shows up to tell her the truth.

The girl is never called “crazy” (she and Grandma actually prefer that to “disturbed”), and the scenes with the ice cream and Grandma catching her pretending to sleep are vivid details I remember distinctly.

Does this ring anyone’s bell? Any help would mean so much — thank you!