I'm not going to lie and say I know everything about this kind of stuff, but I think your nightmares might be related to some sort of past life trauma where you were betrayed by people you trusted. I had some similar issues with having nightmares about someone close to me doing terrible things and one day I got a psychic reading from a friend and past life stuff came up and she said that person had done stuff like that to me in past lives without me even having to bring up my dreams.
I trusted her because she actually brought up another life that I had dreamed about. At first I thought it was a dream and I kept it to myself, but then a few weeks later my bf at the time had the same dream, only he was a different person in the dream and he told me about it and we were amazed. And then to top it off, when I got a reading from that lady she described my dream exactly and that's how I know all this stuff isn't just bs.
Some ways you could deal with this is perhaps getting a past life reading by a person who you know is reputable, or pay a bunch of money to get past life hypnosis. I hear past life hypnosis works really well but I wouldn't know because I paid for it once and when I went under all I could do was shake and cry and feel the absolute worst fear of my entire life so the hypnotist brought me out but I still had to pay for it and it was a couple hundred dollars. I also tried past life hypnosis on myself once before that incident and once after with similar results, though no where near as bad.
If neither a reading or hypnosis is an option for you, it's okay, all you have to do is remember one important thing. Sometimes people are in your life to correct wrongs they've done you in the past. You can't remember your past lives for a reason. It's to wipe the slate clean so they can have the chance to be good to you and nurture a loving relationship with you in this lifetime. This is how we learn and why we keep coming back.
The important thing to remember is how these people have treated you in this life. If they've never given you any reason not to trust them then you should forget about being afraid of these people, because that's not them anymore.