In Keisha’s Shadow by Sandra Barret

Dumped by her high school sweetheart for not being out and proud, bi-racial Tori Kahl struggles with college life, her demanding mother, and the legacy of her dead sister Keisha. Her only escapes are riding her horse, drinking, and cutting herself. Then Ashley, the brash and flirty new boarder, shows up at the stables and not only challenges Tori's top rider status, but shakes her world of self-pity as they cope with the pains of growing up.