They Call Her Regret by Channelle Desamours

In this young adult speculative mystery, a teen must find a way to free a cursed witch in order to save her best friend before time runs out.

Every year horror-loving Simone Washington throws an epic Halloween party for her classmates. Party-planning is her favorite escape from the dark secrets in her past, and this year, she’s taking things up a notch with an invitation-only event to celebrate her eighteenth birthday―something that will leave the halls of Pinegrove Academy flooded with gossip about the big ghoulish bash. The overnight stay at Doll’s Head Lake will be filled with spooky pranks and scary stories told by the fire―including the legend of a local witch named Regret.

But those dark secrets from Simone’s past are forced to the surface at the party when her best friend Kira drowns under questionable circumstances. The witch appears and offers Simone a deal: if Simone can figure out how to release Regret from the curse trapping her at the lake within fourteen days, all of Simone’s regrets will be erased. If Simone accepts, Kira’s life will be immediately restored. But if she fails, Kira will die again―and Simone will be the one to kill her.