Someone might be getting away with murder in Romy Hausmann’s novel, Sleepless, an ambitious cat-and-mouse thriller, about guilt, coercive control, social inequality, retribution and justice. It’s over, my angel. Today I’m going to die. Just like her. He’s won.It’s been years since Nadja Kulka was convicted of a cruel crime. After being released from prison, she’s wanted nothing more than…