。
She had to silently endure her own misfortune.
Literal
[topic-は] my-own-self [genitive-の] misfortune [to-に] fixedly must-endure was.
わが身 is a literary first-person possessive ('my/one's own self/body'), used in narrative contexts where 自分の身 would feel too plain — the わが+ form has classical-poetic resonance, often turning up in proverbs (人のふり見てわが身を直せ). 不遇 ('misfortune, ill fate, being unappreciated') describes the broader sweep of unfair circumstance, especially being denied recognition or opportunity. じっと is a state mimetic for staying motionless, fixed, enduring — here it modifies 耐える ('to endure') with the sense of bearing something silently, without flinching. ねばならない is the formal/literary 'must' construction, the elevated cousin of casual ~なきゃ. The whole sentence has a deliberately somber, almost classical narrative tone.