A Reason for Being (1989)

She'd unleashed his fury with her jealous lies Ten years ago 17 year old Maggie had fled her beloved Deveril House--driven off by Marcus Landersby's savage outrage. Her falsehoods, an attempt to hang on to Marcus, her attractive older stepcousin, had backfired horribly. Now Maggie had returned to her home. Reluctantly she'd been drawn back by an urgent letter from Marcus's schoolgirl halfsisters, Susie and Sara. The two motherless girls desperately needed her. But Marcus now 37 would never tolerate Maggie's presence. Too many bitter memories stood in the way--and so did his malicious fiancee, Isobel....