My neighbour is trying to kill me?

Im not being paranoid. A few years ago, his wife left him for me, so their has always been hate between us. Addtionally, a few days ago I got the job he was hoping for. He has now been giving me sighns of trying to kill me. For example, he has left several notes on my doorstep such as "Get ready for hell, cause ur soon going to be sent there". A few days ago, he ran over my dog, and left its cut off foot at me door with a note that said "Next time it will be ur foot". I cannot call the police because I have no proof its him.