You Favor Your Adopted Sister. Why Are You Crying Now That I Want a Divorce?

I've been married to Pei Yanqing for three years. He's wonderful in every way, the perfect husband. But that's only when Bai Zhizhi isn't around. As hard as it is to let go, I've decided to walk away. I can live without love, but I can't give up my self-respect... Still, shouldn't Pei Yanqing be happy that I asked for a divorce? Why is he crying? And why does he say my heart is made of stone? He must have lost his mind.