The Other Twin by Karen Roberts Turner
"Growing up, Ebony Morgan and her sister, Essence, were textbook twins. From their appearance, to the way they walked and talked, Ebony and her sister were indistinguishable. But as they got older, Essence emerged as the leader of the two and Ebony became less of a mirror image and more like a shadow. Now at college, Essence is no longer interested in 'twinning.' In fact, she wants nothing more than to put distance between her and Ebony. That desire leads Essence down a troubling path. Devastated at her sister's abandonment, Ebony is trying to build a life of her own. But Essence's 'mean girl' attitude may prove more than she can handle. When heartache and heartbreak enter their lives, both girls find themselves navigating adversity that could turn their worlds upside down. Can their twin bond withstand the ultimate test?"