Complex sentence: Prior to her death, she shared the story of her marriage to Byron with Harriet Beecher Stowe who published the account in 1869 and all but destroyed Lord Byron's reputation.
Split into simpler sentences: Prior to her death, she shared the story of her marriage to Byron with Harriet Beecher Stowe, who published the account in 1869. In the event, she all but destroyed Lord Byron's reputation.