Quit Job

So I quit my job becuase my boss yelled at me for being one minute late , she also extended my probation period basically saying if I'm one minute late again I will be sacked. I have never said no to working extra hours even though my contract is four hours , and I also worked over time which I felt was unappreciated. I felt she was discriminating as it felt she loved everyone except me. My mental health has sky rocketed down and I've never felt this down in ages. Thank god I've finished working there.