Alpha's rejected mate

Elena was treated like a slave and accused of killing her parents that she loved dearly.
Her first meeting with her mate forced hopes through her dying out, finding her even with her life right on the line.
However after finding out the mate that she thought was going to save her from her sufferings, he rejected her, taking her step sister, Kathrine as his chosen mate instead.
Elena is broken to her bones. After finding out about her pregnancy for the Alpha and becoming a famous doctor.
She returns to the pack where the Alpha needs her medical expertise to cure him from not a disease but his rogue state