The Mirror by Nora Roberts

When Sonya MacTavish inherits the huge Victorian mansion on the coast of Maine, she has no idea that the house is haunted. The footsteps she hears at night, the doors slamming, the music playing, are not figments of her imagination. In her dreams she sees glimpses of the past. In the present she finds portraits of brides. And when she has visions of an antique mirror, she is drawn to it, sensing it holds dark family secrets.
Then one night the mirror appears and Sonya glides through this looking glass, into the past—and sees a bride murdered on her wedding day, the circle of gold torn from her finger. It is a scene that will play out again and again—a centuries-old curse that must be broken—and a puzzle she must solve if there is any hope of breaking the curse.