Complex sentence: The scheme unravels and Clay's mother Lilith realizing what has happend sacrafices herself so that Clay can live, having barely survived the surgury and attempt on his life, she commits suicide and her heart is switched for the sabotaged one.
Split into simpler sentences: The scheme unravels and Clay's mother, Lilith, realizing what has happened, sacrifices herself so that Clay can live, having barely survived the surgury and attempt on his life. She commits suicide and her heart is switched for the sabotaged one.