Saved By the Highland Beast by Lydia Kendall

Two people that think they’re unworthy of love…meet each other.

Lady Sophia’s life is in danger: her stalker, who has been sending her love letters for years, is closing in on her. So, she decides to take a job as a tutor to the most dangerous part of the Highlands: Laird McGill’s castle.
Laird Dean’s son has driven away five tutors so far. And the man is desperate to find a woman to take care of his offspring. But the Englishwoman he hires makes his blood boil and his icy heart melt…
Dean soon finds himself unable to let Sophia go. And when the threats on her life continue, he knows he must protect her, even if it’s with his own life…