Shattered Vow by Eva Chase

We vowed to escape together. I broke that promise. Now the men I loved just might break me.
There were six of us. Caged, turned into monsters, and tormented with brutal tests of our horrific emerging abilities.
We had only each other to count on… until our escape attempt ended with one dead, the others recaptured, and me dragged away into a different nightmare.
Now I’ve finally fought my way back to rescue them. Except the men I set free are hardened, beastly versions of the devoted boys I remember.
They see me as a traitor and a murderer—but they refuse to let me go now that they have me back.
They have no idea that the greatest threat may be the new darkness that’s woken up inside me.
I don’t know how to control it. And if these men break me, I could destroy us all.