Tired of my moms toxic behavior

I think my moms toxic and I have been feeling like this for a while now. Shes going back to school and I try to help her as much as I can with her homework. But then I feel that sometimes she manages her time poorly and relies on me to do all of her work. Which is frustating but I do it anyway. Today she had 3 assignments to do at the same time and I ALWAYs tell her not to wait til the last minute. She works 3-11 but she can easily spread her assignments so shes not rushing the last minute.

Basically she asks me to do one of her assignments so I am like mom Why did you wait until the last minute. Then I realized that her professor drops the lowest assignment cause I remember reading that in her syllabus. So I told her to not do this bc it can be dropped and her grades will not be affected she has like a B+. But She lashed out at me. Told me that I am giving her terrible advice and how dare I even suggest that to her. Then she goes on to tell me that I am mean, i have a wicked heart and God will never belss me.

She was talking about me to my cousin. Started crying telling him how I am not helpful that shes trying to do everything to better our lives but I am selfish and I never help her.

How does a mom think that her own child is selfish or evil I have never given her a reason to think of me like that?? I am a pretty good person honestly. I respect her. I help out around the house all that. I listen to her when she has problems. I am always there for her. It really bothers me bc I just do not see how bad I am to her. She has been like this towards me since I was young. She always thinks the worst of me and im getting sick of it. She makes me look bad and evil in front of everyone yet I am not. I dont understand