The movie is called "Entity". There are ghosts/spirits that have sex with humans. I think they are called succubus or something like that.

There was a thread about them on GLP awhile back. Some people claim to like the encounters and even seek them out. They get what they deserve I guess. I don't know why these types of spirits seek out an innocent person when they have people actually seeking them out.

If you are telling the truth then you need to get help. Maybe you could find a reputable medium who could tell you what is going on and how to get rid of the thing or else go to a parapsychologist. If you have a religion maybe you could talk to your priest/pastor/rabbi or whatever. They may have some information.

Your only other option is to fight it on your own. I would get help if I were you.