My illusion!

Has any of you ever had it? An illusion? Well, I did...
I was about 16 or less when I had a high fever. Usually with me, a fever gets me at least once every year. I was told it was a good thing since it strengthens the immune system and as your body gets used to it, it could fight it off the next time... yes yes... these were advantages, but with THIS fever... what happened was frightening and went as follows:
I was spending most of my time in bed that day... and as night fell I was pretty tired of lying down... nevertheless I got up took my medicine and got ready to go to bed again... I was feeling alright except for the little body heat I had that was kinda disturbing. For the rest I was sleeping soundly until somethin suddenly woke me up in the middle of the night and I lifted my head looking around me... (my room was arranged in a way that my bed was facing the window in which also my sofa was placed facing me) and there I saw the shadow of a man sitting with his arms spread and legs crossed. At first I didn't take it seriously and ignored trying to go back to sleep... but when I opened my eyes the second time the figure was still there. A little surprised I thought it was my brother and looked at the time being around 1 oclock. I gave him a look and said: "What are you doing here? Do you know what time it is? get out!"
There was no response and the figure remained still... looking back at it I sat straight on my bed almost about to shout when I realized the figure looked nothing like my brother! My heart leaped and I actually had the guts to ask: "Who are you?"
The shadow just looked back at me without responding and suddenly I started seeing images of what looked like his family approaching me with knives. I tried so hard to make the images go saying it was only a dream... but it didn't work, I was fully awake and the images were still there. Ofcourse you could imagine I ran to my door and unlocked running to my parents.
I banged on their door and they opened seeing me in a miserable state saying: "Baba, there's someone in my room! Please help!"
My dad ofcourse walked before me to my room and switched on the lights. The room was empty. And the sofa the person was sitting on was also empty. My eyes widened and I told my dad I could've sworn someone was sitting there. In the end my dad spent the night sleeping in my room since I was too scared to sleep alone. Next morning they asked me what happened and I told them. Later they said what I saw was not real but simply an illusion you get when your fever goes over 40 degrees. You start seeing things that aren't really there and they looked damned real! That was it... and later my brother said I was lucky to have experienced something like that... what a dope! If only he knew how terrifying it was... worse than any nightmare!