I understand how you feel. I was blessed with more loving parents but extended family is like this. When you have been treated like you are less than human by someone, it is extremely difficult to process that trauma. The best way to get it out is to write it out. Let the anger go through pixels or pens.
I do have a suggestion at that point. Try to figure out what the family, cultural or mental health factors were that contributed to your mother’s behavior. I have been trying to understand my relatives in context. Influenced by English poor laws, an English class system and even historical German culture.
I haven’t forgiven my relatives yet. I am still angry and bitter. I think it is because I am still traumatized. But when I write it out I get better and when I understand it I get better. So keep doing those things and you’ll feel better, too.