I can kinda relate to what you are going through. It's the very definition of hell. The only way I was able to overcome such an obsession is to make a new one - so explore an activity you haven't before and something that excites you, something that no other person can take away.
Do you know what you want out of life? What would you want to do that does not depend on other people? Career ambition? Things you want to do before you die? Go to Europe? It can be anything.