Into the Darkest Corner by Elizabeth Haynes

Catherine has been enjoying the single life for long enough to know a good catch when she sees one. Gorgeous, charismatic, spontaneous – Lee seems almost too perfect to be true. And her friends clearly agree, as each in turn falls under his spell.
But there is a darker side to Lee. His erratic, controlling and sometimes frightening behaviour means that Catherine is increasingly isolated. Driven into the darkest corner of her world, and trusting no one, she plans a meticulous escape. Four years later, struggling to overcome her demons, Catherine dares to believe she might be safe from harm. Until one phone call changes everything.
This is an edgy and powerful first novel, utterly convincing in its portrayal of obsession, and a tour de force of suspense.