Why do people assume things about mental illness? Why do people see me as the problem? Why am I the one faking? Why do I feel so needy, yet when someone does come I wanna push them away?

I'm struggling to cope. I have a dad who loves me, but doesn't understand me. I have a mom who uses me for money who I havent spoke to in 7 months. And I have a friendship that's falling to pieces. Everyday is like a roller-coaster. My emotions flip and change like a light flickering when it's broken. I am that light.

My dad doesn't understand mental illness. He believes that it's just a sick fantasy that doesn't really exist and that people choose to live the way they do. He sees me as an idiotic disappointment because I went to the 'extreme' of self-harm to keep me company. My dad is the kind of person who will tell you If he believes you are wrong. But he tells me I'm wrong about ME. That I'm fantasising my illness and issues. Sure, I haven't had a diagnosis, but my mom couldn't be bothered to take me to get one whilst living with her as she was too drunk to function. And I see no chance of my dad taking me, he thinks it's a waste of time and a way to make him look petty.

 Everything is driving me nuts. Constant triggers almost everything reminds me of my alcoholic mother, People who say they're here for me when they're not and the thoughts. The sick, twisted, intrusive thoughts. I keep getting these thoughts that sound so real it's like someone is next to me whispering them in my ear. I'll look at something and all I can think of is how I would use it to k*ll myself. I have no intentions of suicide at the moment but a while back I was quite suicidal. Its like the suicidal parts gone but the thoughts stay. I also get paranoid ones. 'oh you did that wrong, you moron no one likes you' 'you may as well stop trying' 'you're so annoying they hate your guts so much' 'they only go with you because they feel sorry for you'. Those are just a few examples of what I get. My attachments are bad too.
I'm extremely attached to one of my teachers (in one of my previous posts for more detail) and it's just getting worse. The days are going so quick and it feels like only 3 months ago since I started year 10 when in reality it's been 8 and I this time next year I'll be gone. Unless I do A-levels. However this then come back to the stupid thoughts making me believe I'm not good enough.

Some people say bad words don't hurt you if you let them, well it goes the same for positive words too.

I need advice really badly as this at the moment is my only place to vent and express my true emotions.  Thanks for reading it you got this far. :)