How to not be afraid of the basement?

I am always afraid of someone breaking into my house and ghosts and bugs. I am always so afraid that I have trouble sleeping every night. There are three doors in the basement that lead outside (not including the door at the top of the stairs). My mother is making me a room in the basement for multiple reasons; my siblings wake me up almost every morning by yelling (at each other) and running around and I share a room with my six year old sister who won't clean any of her stuff up- and if she can work a Play Station, a Wii, an iPhone, and an iPad, I am positive she can clean up after herself. She is so filthy that we have had ginormous centipedes, spiders, and maggots in my room! Also, I am 15, so I should have my own room. While my mother is working on my basement room, she is allowing me to sleep in her room or living room (which are both in the basement as well). I want to go down there tonight and watch television, but I am still afraid to be down there. Sometimes, I check the entire basement (while carrying a knife or something) and there is no one there, but I still feel like there is something or someone down there. When I go up the stairs, I feel as if I am being chased and start to run as fast as I can while frequently checking behind myself. How can I stop being afraid? I'm a 104 pound 15 year old 65" tall girl- I can't do much to stop "evil."

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