Sorrow’s Sin by Helen Allan

Twelve enslaved planets – one woman to free them all.
Hunted and reeling from the destruction of one she loved, Sorrow must find refuge amid the human survivors of a planet in turmoil.
Taking shelter in the fortress her mother once built, Sorrow hides from the Sin who prey upon humans for their flesh and those Earthborn that seek her death.
Seeking to create peace between the species she resolves to take control of the time gates, to enable the enslaved humans to return to Earth and break the power of the Earthborn.
But a new enemy is coming, one none of them anticipated.