Why is Mrs. Catherick financially supported by Sir Percival in the novel, The Woman in White?

Mrs. Catherick, Anne's mother, lives alone at Welmingham, supported by Sir Percival's hush money after a scandal arises when she and Sir Percival are caught in the vestry. Mrs. Catherick is wrongly accused of infidelity and her husband leaves her with her daughter to face decades of scorn by the townsfolk. Bitter and ruined, she basically abandons her daughter to the care of a neighbor, Mrs. Clements.