。
She silently endured his abuse for years.
Literal
She [topic-は] how-many-years-of duration his abuse [to-に] silently endured.
Three pieces give the sentence its weight. 何年もの間 ('for many years, for years on end') compounds 何年も with の間 to mark an extended span of time. 黙って (te-form of 黙る, 'be silent') is used adverbially — 'silently, without saying anything.' And ~に耐える ('endure ~') takes its object with に, the same に you see with ~に苦しむ. 虐待 ('abuse, cruel treatment') is a heavy Sino-Japanese compound covering domestic abuse, child abuse, and animal cruelty alike. The line carries the somber weight of a description of long-running domestic mistreatment.