Butterflies That Never Die by Aldara Thomas

In Leirianor, a land of shapeshifters, the Great Ladies of Death and Night once fought to the end for the throne. For thousands of years people have venerated them like goddesses, knowing that one day their Heirs would arrive to finish what they started.
In present times, seventeen-year-old Hannah Khoren uses her newfound powers to open a portal into Leirianor. Her plan is simple: find her missing best friend and return to her ordinary human life on Earth. But when Queen Arabella, assailed by fanatical rebels, discovers Hannah’s identity, she marks her as a threat that must be eliminated to protect her life… and her throne.
Hannah will have to untangle the web of intrigues woven around her and make allies out of enemies if she doesn’t want to end up dead. All while trying to control a blooming power that threatens to turn her into a monster. But if she wants to survive, she might have to turn into a monster anyways.