Woman Obsessed (1959)

"She hated the child whose life stirred within her...because it was part of him whom she loathed and despised..."

After her husband dies in a fire, a woman (Susan Hayward) is left to tend for her young son and the family farm on her own. Soon, she takes in a drifting handyman, they fall in love, and a resentment begins to build between the son and his new "step-father" who treats the boy harshly on purpose to prepare him for life on the frontier.