Who is Eboline from Mudbound and what is their importance?

Eboline is Henry's sister. She is described as a conceited, rude woman, who insults Laura and her family in the days before the wedding. Eboline married well, but her husband made some bad investments and cannot face telling her.... rather than tell her, he kills himself on Christmas. If not for the death of Eboline's husband, Henry might have waited longer to buy a farm and might have bought a different farm. However, with Eboline in need of Henry's care, he decided to buy the farm, setting into motion the events that would lead to his father's death.