Living with a very unstable parent

Hi guys, so this might be a very long post. I have been experiencing all these problems for a very very long time now, and I honestly have no idea how to go about dealing with this issue. So here goes.

My mother is an extremely unstable person. She loses her temper very easily over the smallest of things, and her reaction to it is incredibly huge. For as long as I can remember, she has always been seen to be extremely fierce, and at some times, abusive. I remember as a child, not knowing how to do basic math problems, she would lose her patience with me and instead of explaining the concept to me, she has done things such as flip me off a chair, causing me to fall to the ground, ripping my book into half and throwing it at me, as well as being hit multiple times, sometimes with items such as clothes hanger or a cane.

One of the most vivid memories I have of such abuse was when I was 14 years old. I had forgotten to photocopy some work from a friend despite multiple reminders, and it gotten to the point that one morning she lost her temper and actually scratched my skin, pulled my hair and ripped my uniform, tearing out the buttons (it was a morning when i was about to head to school). I had to go to school with messy hair and a torn uniform, avoiding questions and glances from people who wondered what had happened.

Another incident was when i was 16 and had a boyfriend then. I didn't tell her about it, and when she found out about him, she lost it at me (i come from a rather conservative part of Asia where i suppose relationships are only meant for the older people) and first tried to chase me with a key, threatening to scratch my face with it in order to disfigure me, such that nobody would ever want me. On multiple occasions, she has even threatened me with a knife.

Naturally, you can guess that she is extremely controlling of my every move. What friends I make, who i go out with, if i can even go out, how long i can go out for, my dressing, my behaviour everything has to be approved by her. I am currently 20, and while the restrictions have gone down, i still suffer deeply from all these past incidences. My self esteem is extremely low (as growing up, i have been told that im ugly and stupid so many times by her), and i have this deep fear of speaking up in public for fear of what people may think or react to me. I also currently have an amazing boyfriend, whom i have yet to tell her about, but im guessing that she would definitely not approve of him (as her is of a lower education qualification than me) and may react extremely adversely when i tell her about him.

I have tried talking to her about this but to no avail. My dad is a push-over and he always sides my mum. There have been many times when im being punished by her for something that wasnt my fault to begin with, and he would come and hit me just for the sake of hitting me until my entire arm turns purple from the bruises (then i would be forced to wear sleeved clothings for the next few weeks)... I also come from a country where it is looked down upon to go against your parents no matter how abusive they may be, as we are taught from young to respect our elders and to trust them. Thus, going to the authorities about this would simply mean that i would be shunned by my other family members. Moreover, I cannot go to any of my family members about this issue as they would side my mum and assume that i must have done something to deserve it. Also, i am still currently studying and financially dependent on my family, which makes moving out a little tougher. Moreover, even if i did have the financial capabilities, moving out is not an option as she would probably track me down and force me back home.

I actually have no doubt that my mum loves me. I know that at times she may think that she has my best interest at heart, However the methods she resort to to ensure that i end up 'perfect' seems harsh, and at times when she loses her mind, i honestly think that she may one day kill me in a moment of rage and then regret it terribly after. Everytime after she has punished me and is in a better mood, she begins to apologize and try to make it up to me, only to lose her temper at me again days later.

I no longer want to live my life like this. It is causing me so much misery and pain, and yet i dont know how i can continue to deal with this situation.

Sorry for the long rant