Secrets of the Celestial by Amber Grosjean

Jenna has lived many lives, choosing to return to Earth over and over again through the heavenly waiting area known as the Soulport, a bridge between Heaven and Hell. But during her last rebirth, a guard's blunder sends her to Earth as a baby named Jaime—with her memories completely intact.

For twenty-one years, the seal holds. Then, it cracks.

Suddenly, Jaime (Jenna) is losing her grip on reality. Her head pounds with the screams of past deaths, losing her job and her friends as the floodgates burst open. When the angel Mary breaks through the veil to correct the mistake, she offers Jaime a final ultimatum: let the memories go or keep them and risk destroying her mind forever. In a world where her own identity is fracturing, Jaime must decide what her soul is truly worth.