Dream of sexual, keys

The first thing I remember is being in a boarding school kinda house with at least 15 other girls and a headmistress. Suddenly, a guy (about 25-35 years old) walks in and starts shooting everyone. The headmistress and I are the only ones left, so we run (not together). I end up in the garden and try to ride a horse that is standing there (I did some horsebackriding a couple of years back) but fall off as the horse jumps. I remember that there is a school car and run inside to grab the keys. As I turn to run towards the car, he stands there, brings the gun towards my head but doesn't shoot me. Instead, he takes my head into a headlock and guides me outside where the headmistress is running for her life. Suddenly, i realise that we're not on the countryside in some old boarding school but right outside of my house. He shoots the head mistress, he takes me back inside and some sexual activity takes place. After that we run together and when I'm freed by the cops, I help him escape and we run off again.