Your ex-girlfriend died three years ago in a car crash. She was pregnant with her first child from her husband, now her widower, whom she met two years after you ran off. Her death and the death of her unborn child condemned her parents and her widower husband to years of pained mourning, relieved only by stretches of numbing exhaustion. The past year or so has been the first where it could be said that everyone has begun to move on. Her former husband has remarried (her parents having attended the wedding), and her parents have found they can sometimes go months without succumbing to a spell of grief over her absence.
Your postcards aren't helping. When you started sending them the year after you left, while she was still alive, she appreciated the first few. She appreciated that you weren't able to just expel her from your life without a second thought. She never bought your extensive explanations for why you had to leave, but they offered her some small vindication that what she felt for you wasn’t entirely one-sided.
Once she met her future husband, she of course tired of your postcards, usually responding to them only with a pitying chuckle before tossing them in the trash. She thought it was cute that you would tell her each time you started a new job or arrived in a new town, but she could tell you were simply lost and might never be found.
Once she died, however, and the postcards kept coming, her parents and her former husband came to despise you with all the emotion they could muster. Their hatred for you was refreshing. It was a relief to feel something besides absolute loss.
As her parents' pain began to subside, a postcard from you was all it took to bring the loss of their daughter back to the forefront of their minds. They knew you couldn't know that she was gone, and that you were responsible for so much hurt, but when one or the other would burst into tears at the sight of their daughters' name in your handwriting, they both wanted nothing but to see to your own untimely death.
Her father has taken measures. Not to kill you, but he's paid a man to find you and make you bleed. He's paid an additional three hundred dollars to guarantee that your hand is broken. He couldn't remember which hand you write with, but he asked that your right hand be broken. The man will visit you tonight in your room above the bar. He'll tell you first that your ex died many years ago, then he will beat you with a baton and shatter your right hand. When he leaves, everything will be different. Your ex-girlfriend will be dead, and you'll have spent the previous three years stirring pain in the hearts of those who loved her more than you ever could. This is going to be the thing that finally makes you stop goofing around so that you can go back to school and get that degree.
Happy Postcards Day!