The Queen of Nothing by Holly Black

After being betrayed and exiled by her treacherous husband, King Cardan, Jude Duarte has spent her time in the human world, nursing her wounds. But her return to Faerie is inevitable when her twin sister, Taryn, shows up with a desperate plea for help.

Back in the treacherous High Court, Jude finds that Cardan has made himself a recluse, the land is on the brink of war, and a deadly curse threatens everything she fought to gain. Forced to confront the husband who wronged her, Jude must uncover a conspiracy, outsmart her enemies, and reclaim her power—even if it means facing the greatest betrayal of all.