A childhood belief about imaginary friends

Ok, when I was seven I started to see "Alex". First I say his dog. Then when I was eight I saw him. He had a black hat on and dark brown trousers with a black jacket. When I was eleven I was in tescos and my mum was in the video Isle when I saw a film called the Martian. The guy on the box looked like Alex. That's weird I though. I said to mum, hey mum, that film looks good, she ended up buying it and we watched it that night with my siblings. When I was nearly thirteen I saw him standind in my bedroom door at midnight, only he had taken his hat off. Please talk to me. He said. Who are you I said. I want you to leave me alone! I said as I got up and sat on my bed. He walked in to my room and pushed me back down on to my bed and wouldn't let me get up. He held me down and I shouted at him loudly. Then he got in to the bed and I was just about to slap him round the face when I heard my mum get up. I stayed still and he still held me tight. I was getting very angry. When mum was back in bed he got on top of me and I tried to kick him. I don't remember any more than that. I dont see him often anymore, but I hear his voice in my head.