First of all, I am sorry that you are having to endure this while you are still in high school. Things are difficult enough nowadays without having a mother who seems to be making poor decisions and seems unable to self regulate her emotions.
Planning to move out when you finish high school is the right goal to have, and I’d put my effort into doing what you can do to become more independent. This may be going away to college, finding work and living with roommates, or finding family members you can live with until you get on your feet.
But in the time you have left at home I would encourage you to have a private conversation with your dad about your concerns with your mom.
He must be feeling some of this as well, and having an alliance with him and his understanding and help may be very important. He chose your mom as a partner and may need to hear from you how difficult it is to watch and experience her poor behavior. The fact that she had had a stroke, is angry without provocation, and fails to take responsibility for her own actions are all serious indicators that a medical evaluation may be necessary. Talk to your dad about getting your mom to see a physician.
Wishing you patience and peace,
Proof Positive Blog @ PsychCentral