Inescapable Darkness by Raven Wood

Six years ago, I saved the life of a mafia prince.
Biggest mistake I ever made.

Because now, the people who wanted him dead have realized that he is in fact still alive, and since I am the one to blame for that, my head is now on the chopping block too. In order to evade them, I decide to hide in the one place they would never expect me to be. A school for assassins.
Pretending to be a mediocre student, I hide my true skills and change my appearance so that no one will notice me. But there is one massive problem that I did not see coming. The mafia prince I saved is there too. And he recognizes me.
Keeping my identity hidden becomes increasingly difficult when he is doing everything in his power to force me to admit who I really am. If I don’t reveal my identity to him, he might actually kill me. But if I do, our hunters will kill us both.

So I only have one choice: withstand his dangerous attention and hope that he loses interest.

But the problem with a lethally powerful man like him is that once he sets eyes on his prey, he doesn’t stop until he gets what he wants.