Dear Megan, I'm so sorry that you have to go through this bad experience.
I know at this point it won't be of any comfort to you to know that you are not the only one to have a "toxic mother." I taught at the college level for 25 years and always kept a box of tissues handy for all the students that came to cry in my office, usually about family troubles. One of my graduate students had surgery for ovarian cancer, twice within six weeks, and her mother couldn't bother to come from WV to Connecticut. I brought Lisa to my house for her recovery. Her mother called on the phone and asked to talk to her without even saying hello to me, as if I were running a boarding house.
In spite of general belief, not every woman is born to be a mother. The ones that are not, but have children, can do a lot of lasting damage.
You are 16, in another two years you'll be able to finish school and become an independent young woman. In the meantime, do not let your mother, under any circumstances, make you feel guilty for anything. That is a game that some mothers play to perfection.
I do hope you can find some adults to help.
With many hugs and best wishes for a solution to your problems.