That sounds terrible. I cannot imagine what it must be like.

Some thoughts: - As a child I had a lot of nightmares too. My parents couldn't handle it and yelled a lot or acted annoyed when I was running dangerously fast down the stares again. Later I learnt that it had a lot to do with stress in life and not being able to express emotions. And I am pretty sure that my parents being a-supportive just made it worse. It is only when I started living on my own that I was able to handle or let go of the many fears. Even now when I am home alone at my parents place I'm still very scared. So my conclusion being that your fiancee calling you the devil aint exactly the right support, talk to him about it. He should show love and be supportive. The same for your matter calling it a gift from god. It only makes you feel more like a freak, which you already feel enough, since your goal of your post is to search for people with similar experiences.

-I don't think solely drugging you will help. Meds can be beneficial but only in a treatment which main focus is not drugging. I would suggest that you looking for a good therapist (if you haven't already done so). You might want to try something with mindfulness, but I wouldnt suggest doing that without the followup of a therapist. Try to get an understanding of what troubles your mind and causes these dreams, so you can comfort your inner child(which is just a metaphor).

-modern medicine and psychology offer the benefit that causes are not searched anymore in supranatural beings or forces. So in my opinion you're not possesed by the devil or something alike, your psyche is troubled and can be helped to resolve issues. In other words, you're not determined by something which is impossible to resolve.

These advices probably aren't new to you, these are just the thoughts that popped in my head.

I wish you the best of luck!