The Blood Oath of Blackbriar Academy by Olivia Ash

Agatha is up to something, and with a witch that powerful, you can bet it won’t be good for me.
She’s always wanted to dig her claws into Milo, and when he starts acting — well, odd — I can only assume her shiny new necklace has something to do with it. It reeks of enchantment, and as Milo gets lost in the depths of her spell, only I can save him.
Messing with me is one thing. But messing with my men? That’s unforgivable.
One by one, my men are being removed from my life.
First Milo. Then, Gideon. Powerful people are behind this, pulling the strings on my life in an effort to take everything I love away.
Which means Soren and Jesse are next on this deadly hit list.
You mess with my men, you mess with me.
What the people hunting us don’t realize is you don’t want to mess with me.
The people after us want war.
Well, I can give them that.
Ready or not, here I come.