This is probably going to be a wall of text, so I apologize ahead of time.
First of all I'm not insane or what I experienced did happen.
Years ago, when I was in tenth grade I had reached my breaking point and was starting to feel as though I was going to lose my sanity, and gain another personality. This was before I actually made a deal with the encroaching madness, and retained my sanity.
Before I made the deal with my mad self, I was in an incredibly fragile state of mind, and the energy (aura) I generally emit, which is usually incredibly strong, was very weak. Because it was so weak I was susceptible to get psychically attacked.
There are things known as psychic vampires, and there are different forms for them, they usually are people (many don't even know they are psychic vampires) who drain other peoples auras to make up for what they can't generate themselves. There is also astral form of the psychic vampire, the most notable form of a psychic vampire is known as "The Old Hag", there are other types but that one is the best known. An encounter with an astral psychic vampire is a terrifying experience, but it happens in multiple steps, and usually happens from about 1 A.M. to 5 A.M.. The first sign of an attack is waking up to a feeling of dread, or intense (primal) fear. Second sign: You can't move your body, also known as sleep paralysis. Third sign: a feeling of something is in the room with you, sometimes you can see a shadowy humanoid figure (Not a shadow person). Fourth sign: This does not happen in all cases, but you feel as though something extremely heavy is standing on your chest. After a few minutes it disappears and the feeling of dread vanishes, normally you wake back up about an hour or so after an attack, because you were drained of your energy.
Well, what happened in tenth grade truly was terrifying because I was attacked multiple times during the time I was in such a fragile mental state.
One night around 2 A.M. I suddenly awoke to feeling of dread that seemed to be getting closer. About a minute later I saw two shadowy forms come into my room. I was actually able to sit up and look right at them. As soon as I moved I could see them actually step back and look at each other, as though what I did was not supposed to happen. When I was looking at them, I imagined a small dot of light appear where their hearts would be and as soon as it appeared it exploded in a flash of pure white light and ehe feeling of dread disappeared immediately.
About two days later I awoke to a similiar feeling but this one was much more powerful and ancient and it also gave off a feeling of intelligence. When I awoke it didn't feel as though I could not move but more of that I didn't want to. Well, I decided to move my head from under my cover to look, and between me and my window there stood this pure black entity leaning about a foot away from my face. It was a bright night as well, and I didn't have any sort of curtain or shade or blind that might be mistaken as this thing. While stared at me, I stared back at it mustering every last bit of willpower to fight it. About a minute afterwards I blacked out, waking to the sound of my alarm clock going off.
Shortly afterwards I merged with my mad self, and I've never experienced anything similiar to that ever since.