Complex sentence: She is arguably the main villain of the novel, and ruthlessly seeks revenge against the Evrémondes, including Charles Darnay, his wife Lucie Manette and their child, for crimes a prior generation of the Evrémonde family had committed.
Split into simpler sentences: She is arguably the main villain of the novel, she is obsessed with revenge against the Evrémondes. She ruthlessly seeks revenge against the Evrémondes, including Charles Darnay, his wife Lucie Manette and their child, for crimes a prior generation of the Evrémonde family had committed.