Taking Leave

I'm so angry with my boss..........
Previously when I went for interview for my current job, I told my boss that I am still studying & that I will need to take leave for exams & studies.
Know what happen today? This morning, some last minute things came up & I cannot defer it to later or the weekend. Not a problem, I thought. I can apply for leave... So I sms my boss & another colleague telling them that I have something urgent that I need to attend to today & have to apply for a full day leave.
KNN... After 15 mins later, my boss reply my sms. Can you arrange your personal things on weekends. Try to come in in the afternoon. Cannot take full day leave. WTF!?!?!?! How do you expect me to go for my exams then?
Actually I have been arranging a lot of personal meetings during lunch hours or after office hours. And now he tells me to not take leave for personal things?!?! Going overboard boss.... You know that I am going for exams & now you tell me not to take full day leave?
Well, I have prepare my resignation letter. Just need the effective date. Good luck boss.