help

Can someone answer me this? How can people intentionally hurt you, knowing how much you love them. Then sit back and laugh. What satisfaction can you possible get from causing another person pain. Then do it repeatedly.  I truly hate my ex and his fling.  They continuously contact me with pictures of them having sex and they constantly stalk me.  It has been a year now and all I want is peace. i have contacted the police, I have moved and I have changed my number 5 times.  What do I do before I hurt myself so they cant get to me anymore...