My Friend from the Park (2015)

While her filmmaker husband works in Chile, harried young mother Liz struggles to take care of her infant son. Feeling out of place amongst the tight-knit group of other parents at the park, doubted by her husband, and judged by her newly hired nanny, Liz is drawn to factory worker Rosa, a plain-talking single mother she meets at the swings one day. Despite Liz’s liberation upon finding a bold new confidante, the friends’ increasingly apparent class differences, along with swirling rumors about Rosa’s motives and muddy family situation, feed Liz’s suspicions that her new pal might be a sinister influence on her already fragile life.

Source: TMDb