This sweet sickness - Patricia Highsmith

David Kelsey has an invincible conviction that life is going to work out just as he has planned it. Even though his one true love, the brilliant, beautiful Annabelle, has married another man, that can't possibly be the end of their relationship, can it? They can certainly still be friends. And even though she is pregnant with her husband Gerald's baby, that surely doesn't mean she won't one day get back together with David, does it? David is sure she'll take him back, and, under an alias, is setting up a wonderful home for the two of them in a town close by. And everything is just about going to plan until things take a murderous turn, leaving David a desperate man on the run.