LOVED (Book #2 of the Vampire Journals) by Morgan Rice

In LOVED (Book #2 in the Vampire Journals), Caitlin and Caleb embark together on their quest to find the one object that can stop the imminent vampire and human war: the lost sword. An object of vampire lore, there is grave doubt over whether it even exists.
If there is any hope of finding it, they must first trace Caitlin's ancestry. Is she really the One? Their search begins with finding Caitlin's father. Who was he? Why did he abandon her? As the search broadens, they are shocked by what they discover about who she really is.

But they are not the only ones searching for the legendary sword. The Blacktide Coven wants it, too, and they are close on Caitlin and Caleb's trail. Worse, Caitlin's little brother, Sam, remains obsessed with finding his Dad. But Sam soon finds himself in way over his head, smack in the middle of a vampire war. Will he jeopardize their search?

Caitlin and Caleb's journey takes them on a whirlwind of historic locations-from the Hudson Valley, to Salem, to the heart of historic Boston-the very spot where witches were once hung on the hill of Boston Common. Why are these locations so important to the vampire race? And what do they have to do with Caitlin's ancestry, and with who she's becoming?

But they may not even make it. Caitlin and Caleb's love for each other is blossoming. And their forbidden romance may just destroy everything they've set out to achieve....