How can I gain courage to quit my job?

I’m 19 and work at a dollar general as a cashier. I absolutely cannot put my 2 weeks notice in because my manager will make it so tense and uncomfortable. I already hate working with him; I called in sick because I literally don’t want to work with him. I get paid $9 an hour, it’s so unlivable and I’m in poverty. My paycheck every month is less than $300. I’m also in the process of getting my licenses soon. I want to quit but I’m scared of how he will react and what he will say. He often looks at me as if I’m stupid, he’s so condescending, never know when he’s going to be in a good mood, and he’s made comments on my personal life. He’s told me my boyfriend is probably cheating on me, has belittled me, etc. I just want to quit..