I think i had a nightmare...I'm not sure...?!

I know a lot of people will hate or laugh at me for this but...Without going into too much detail

I had a dream which felt like it was real. I could feel the wind the touch of the stone walls from this ruined castle. This castle was from my childhood "Dracula's castle" In scotland. Well... There was this spiral stairway leading down into the dark. And i was always as a kid too afraid to go down... My dad used to taunt me when i was like... 6 By going down the stairs, and i used to cry and beg him to not go down and come back. It really upset me because i was afraid of monsters and i always thought if he went down too far the "monsters" would get him... Well... Moving on, in my dream i went down these stairs and i ended up in a long hallway, it was pitch black but there was a light at the end of the hallway. And i came out into a room with 2 windows and what seemed like a ruined bed, i thought it was a bedroom. The 2 windows had no glass it was open and i walked over to them and looked out. Below the window was a terrifying drop down into the sea with sharp jagged rocks at the bottom... Now... Here is where my dream gets messed up... I felt something hit me on my back. It felt like a foot. And i was knocked over onto my stomach. Then my right arm was grabbed and i was lifted off the ground.

I play video games. And the thing that kicked and lifted me up was a female elite in blue armour.
It threw me towards the window and i nearly fell out but i stopped myself by pushing against the frame of the window and when i turned round the elite and force me into a position where i was sitting down on the windows stone frame. This really was scary because it felt real and i thought it was. I thought i was going to die because the elite had grabbed my left arm while my right hand i was using to keep my balance... And then the Elite leaned close to me and said "Scream and i will kill you" and... This is where i wont go into detail because even explaining it brings shivers down my spine...It...Well...Raped me... And i just sat there too scared to move...I kind of feel ashamed to say that. Even in my dream because i am not the kind of person who sits quietly and takes things. I would fight back physically if someone kicked me in the back... But in my dream i felt immobilized..
Well... Eventually everything went black afterwords and I woke up...But this is when i got alarmed, I noticed there was a bruise on my right arm exactly where the elite grabbed me. And the thing that scared me the most was the bruise was shaped similar to the print of an elite hand. And my back when i got up felt swore too, I have heard that things can happen to you at night where if you bump yourself it causes something to happen in a dream...But i don't understand how a bruise could make the same pattern as an elite hand... But that isn't what i want to know.

I want to know. What the hell could cause a dream like this to..Well...Be a dream? I don't understand i don't watch porn...And that's the truth. I don't have anything to do with intercourse I have a long distance relationship. And i certainly do not like the idea of rape...
Is this classed as a nightmare if you don't like it or want it?

And please no stupid answers i want an honest answer. I really want to know what could of caused this