I can't find this "zombie" movie!

 [Spoiler maybe?] The main character thinks that there are zombies, but he is mentally ill and he has been killing normal people. He even thinks he saves a girl from them but has actually just kidnapped her. You do not get let in on it really until At the end that they're real people not zombies. The guy lives on a farm/ranch out side of town. The girl he saves was in a store(?) in town. I think he kills a cop at the end. It may have been on Netflix at some point, I don't know anything else about the flick. Thanks