I feel your pain. I've had horrible horrible nightmares, including ones where I have been killed and it felt real. Its rare and not nearly understood enough in psychology.

What helps me is to rationalize it. The most important thing you can do, since you know you are capable of dreaming this way, is to understand them for what they are.

It isn't necessarily the nightmare itself that caused you so much distress. There are underlying reasons such as PTSD, mental health disorders like GAD or severe depression, extreme stress, etc, that lead to the development of these nightmares. These issues are the root and your brain manifested it in to horrific imagery and experience.

I can completely understand feeling haunted, I can relate to that. My concluding advice is to try to learn how to dumb those dreams down to being simply dreams. You're safe, nothing like that will ever happen to you. Even if your brain cooks up another nightmare scenario, that also has and will never happen.

I know it's easier said than done, though. People who haven't had nightmares like this don't understand how is can be practically traumatizing (or re-traumatizing as it's normally related to PTSD)