M+O 4EVR by Tonya Cherie Hegamin
Goodreads: There are two constants in Opal’s life: her dad’s grungy green baseball cap, and her troubled pal, Marianne, whom Opal loves as a best friend . . . and even more. But nothing stays the same forever. When Opal receives the horrifying news that Marianne is dead, she suddenly must live her life and make decisions based on the needs of one person instead of two. Only with the help of her family and the story of Hannah, a runaway slave, can Opal begin to free herself from the weight of her memories, her ghosts, and her own truth.