reason you are having dreams about your ex and enemies is because you must be seeing, hearing, or smelling something that reminds you of them. Our brain will automatically pull up memories from our past based on certain stimulus such as sights and smells. The best way to make them stop is to recognized what is reminding you of your ex and your enemies and remove yourself from that being exposed to that stimulus.
I totally agree with the two previous answers . I heard you dream of the very last thought that ran through your mind right before you fell asleep . Clear your head of all that negative nonsense . Good luck .