Revenge of the Corsairs by Elizabeth Ellen Carter

Heav’n has no Rage like Love to Hatred turn’d,
Nor Hell a Fury like a Mother scorn’d.

Rescued after two years as a concubine in an Ottoman harem, former debutante Laura Cappleman faces a difficult journey back to normal life. As she travels to Palermo aboard Kit Hardacre’s ship, the Calliope, she is deeply traumatized – and pregnant by her kidnapper.
Laura rejects the emotional support of her long-time admirer, Calliope First Officer Elias Nash, and her cousin, Sophia, Kit’s wife. She withdraws into herself and her art. Finally, after giving birth, she decides to return to London, hoping to erase tormented memories.
Emir Selim Omar died on the day of Laura’s rescue, but his wickedness lives on in his third wife, Rabia, in whose household Laura was held. The ruthless widow may yet hold on to the power she wielded as mother to the Emir’s only male heir. However, as opportunists pick his empire apart, her child dies.
When Rabia learns Laura has given birth to a boy, the solution is obvious – the concubine is stolen property and so is the child sired by her late husband. She will take the boy and kill anyone in the way.
As Rabia’s assassins close in, Elias – both embraced and rejected by the damaged woman he loves, uncertain she will ever return, and alone in Palermo with the child he has given his name – must take the battle to the enemy. Otherwise, there may be nothing for Laura to come home to.