This sounds very similar to shanebd18's post (compete trauma) the post trip visions are very similar. I know you mentioned sleep paralysis and don't think that is it, are you certain it is not?  There are generally two forms, one where the "sense" of a presence (often evil) is experienced with the paralysis and the other more severe is accompanied with horribly frightening visions. The fact that this is happening during sleep onset really points to some form of the disorder.

A change in sleep cycle can cause SP along with drug use and many other factors. I started getting SP when I was 7about and it used to scare the piss out of me until I learned what it was and started practicing lucid dreaming. Once I controlled it the fear and "evil" presence went away. I also have experienced many different inbetween sleep states that involve odd sensations and visions.

Anyway, sorry about the troubles, you found the right community for support and understanding,  but don't take any medical or other advice that would better be served by a professional.