I 100% agree with you. It is more than ok, it is necessary, for your mental health and well being to 100% distance yourself from someone who is hurtful and abusive; especially if they are family or parents. This is the only way you can work on truly healing and creating the life you want, building the sort of family (be it friends or any relationships you wish to create) that you want to have.
As a new mom, I am so sensitive to the responsibility it is to bring a child into the world. It is hands down the most important thing I will ever do and every decision I make is based around what is best for her. I am lucky to have loving present parents who have been my rock. However I have witnessed first hand what abusive addicts can do to their children, my ex-fiance had two boys I raised for 10 years who lived with us fulltime due to their mother being an alcoholic and addict. It was shocking what she would do to and with them, using them and manipulating them for her own needs. They are now in their 20s going to University and they have both cut off contact from her for their own sakes.
It is sick and horrible and my heart breaks for what you have had to deal with. I wish you much strength and love for the life you will create for yourself by breaking the chain away from your mother. Good luck!!!