。
She gradually started showing hatred toward me.
Literal
She [topic-は] gradually me [to-に] hatred [object-を] show [came to-ようになった].
~ようになった marks a gradual change in habitual behavior — she didn't always show hatred, but over time she came to do so. This pattern expresses the onset of a new ability or habit, and combined with 徐々に (gradually), it emphasizes the slow development of the emotional shift. 憎しみを示す (to show hatred) is a somewhat literary expression; casual speech would more likely use something like 嫌がるようになった or simply avoid such direct phrasing.