I’m so sorry.
All drugs are scary but cocaine is seen as so socially acceptable now, it is really disturbing as it’s so addictive. It is also terribly easy to get hold of.
There are many other parents experiencing the same issues so I am sure you can get some good advice on here.
Anyway, she has absolutely no right to hit you. I’m not sure if you are male or female. If you are female, Women’s Aid forum has a section for women suffering from familial abuse. You could go on there for advise or contact their helpline. Otherwise, you could always contact the police and ask to chat to their domestic abuse team informally. What she is doing is considered domestic abuse/violence.