I lived with my negative brother for far too long. It was very difficult. Even 2 years after he moved out I still get people asking me, "How on earth did you live with that guy?" Everyday was a struggle. The best I could manage was two weeks and then I had to avoid him at all costs. There is no easy solution for living with some one who is extremely arrogant and negative. Good luck. On the upside, you get to work of your tolerance skills.