How to prevent someone from breaking down my apartment door?

Ok so this is the story. I have a very aggressive neighbor that lives right next to my apartment in the same building. The Landlord allows his aggressive behavior because the Landlord is a slum lord and doesn't care. Also because they are related. Recently my shower got clogged and it overflowed to the downstairs. So this neighbor being drunk and high started threatening my life and to break into my house when I left to go to work. I am trying to save up money to move but it is very hard since I do not make a lot of it. I called the police when it happened and they just warned him to stop talking to me. That is not good enough. If it was just myself living in my house I wouldn't worry but I own a small dog, I have a feeling he will do something bad to him. Please help!!!! What should I do? I need to move but can't afford it at this time. Is their anywhere I can go for immediate help or something I can do to prevent him kicking my door in?