How do you tell your parents you think you have a mental illness?

My mom has asked me if I think I have depression, which in my point of view I have always lived with it, but I chickened out and said no. My life has been weird when it comes to emotions. Like when I was younger I used to have hallucinations where there were bugs on the wall and my mirror was melting and it would make me cry to the point where my parents ran into my room to see if I was hurt. I don't have visual hallucinations any more but when I'm home alone I always hear things banging around. I get so paranoid that I keep a hockey stick and a baseball bat in my room to make me feel safer. I am also very moody. At least once a week I go from being so happy to having a nervous breakdown. It always happens when I'm alone and if I feel the sadness when around others I usually swallow it down until I have to excuse myself. I usually go into the bathroom and cry to get the worst of it out. I find it extremely hard to openly tell my parents what is happening to me and idk why. I guess I dont want to come across as a freak. It has been so bad now that I often think about suicide, I see people in my head trying to control my thoughts, i talk to myself all the time always putting myself down, and during a breakdown the color white makes me go berserk to the point where I feel like I'm having an athsma attack. Its like theres two different "me's" where im fine during the day but at night i become my worst enemy. I really need help but I don't know what to do to get help I know something is wrong with me and I want it to stop before I really hurt myself...like how do I tell someone something so painful that has only been getting worse each day when they have only seen me as the hyper happy girl?