Hi there, first off you need to understand what dreams are, they are a series of thoughts, images, and sensations occurring in a person's mind during sleep, so something must have caused you to feel like this...bad thoughts maybe? something on your mind or has happened to someone?
I can assure you it is just a bad dream, and the more you think about it, the more it comes back.
What helps me during times of bad dreams is trying to forget it, think happy thoughts think about something else, something happy great and fantastic, close your eyes and listen to music, music that helps you relax, imagine something...a beach a countryside a forest a city and close your eyes and be in that place in your mind..
There are free audio tapes you can download online as relaxation techniques that may help if you are under stress or have things on your mind that are preventing you from sleeping, they help...
Just don't worry, I've had many nightmares, and they go away, they're not real, they're not going to come true, it's only your mind that thinks that, and when something similar to the dream does happen we seem to believe the dream was real when it is just a coincidence, but rarely do dreams like you dreamt about come true.
You will be fine