First of all, it is great you are reaching out here to this large community! Abuse is very damaging so you have to work extra hard at surrounding yourself with kind and supportive people…because of the abuse you MAY tend towards people who treat you similarly. Discover your Gifts and tend to them… Also, it may help to have witnesses to the abuse somehow. My mother was also very abusive and was mostly so when there was nobody around. People like this are very difficult to deal with…and try as you might, you are not made of teflon. It MAY help to foster some compassion for her if at all possible…as the abuse likely comes from abuse or neglect she suffered…perhaps you can ask her about her childhood…
If you are as young as your icon indicates, you are surely very malleable and can overcome this treatment with some steps: talking to a counselor, member of the clergy, relatives, etc. I detect you are afraid that your mother will know about seeing a therapist and retaliate, but you really must…and at least you will then have a record of it… I also wonder if you have relatives you could stay with for your own safety as you indicate physical abuse. Abuse is a very serious thing and treated so much more so now than when I was a child…you need someone to intervene on your behalf.
Someone above also said to accept her as she is…you can try that, take an emotional step back, and know you are not she! Please take care and keep us posted.