Who is he, why did I used to see him and why don't I see him anymore?

I used to have nightmares when I was younger and whenever I woke up afterwards, standing in front of me would be a person. I don't know who they were or why they were there but I would only see them when I had a nightmare. Sometimes the nightmares were random but most of the time they were the same until a couple of years later. I would be upstairs in a large room in a cot and it would be dark. And every time a man would come in and hit me. I usually would just let him but after a while I could crouch and turn over, cover my head and then wait and after a while he would start leaving. I knew when he was coming because I would hear footsteps and my heart would beat faster. But then, later on I started having the dream in different parts, like about 5 years ago, when I was in Year 5, I would have the dream round the back of the library, and I would hide behind my teacher and crouch and cover my head and he would go. Now, here's the weird part, if he hit me I would wake up, hear the same footsteps and I would pull the quilt over my head and then when I looked again I would see this person and I would hide again. But if I hid from him in my dream and he left, I could wake up and no-one would be there. Also about 4 years ago they stopped the about 2 years ago I had 1 more and now I haven't had that dream since. So what I want to know is, who is this person, why would I see him after I woke up and why he suddenly stopped appearing in my dreams and in real life.