Am I Mean or Not?

Hi people, I am Elaine, and I am Miss Meanner and I hate you and I don't want to be your friend.

Sometimes I feel that I am a really terrible person, feeling guilty after each mean act. For example, earlier on I had an issue with one of my coursemate. We used to be quite close because we're stucked with the same group when it comes to assignments and all. Initially I thought she was really friendly but slowly I felt she is more like the kind who only make friends for one purpose - to leech on your assignments and tutorial answers. At first I still can tolerate such act but slowly I begin to feel she is so rude even when she wants something from you. A "please" seems such a hard word from her even when she needs the answer desperately. But she is also that kind which is "kiasu" always wanna know what you're studying, how's your work going so I thought she is like that because she just wanna be better than the rest. Until one of our mid sem tests, she literally copied another guys answer next to her throughout the test. She made it so obvious, she was copying word by word IN FRONT OF ME! I thought she said she studied hard for it?! And when I attempted to advise her not to copy during the test, she turned a deaf ear. And on the second attempt, I even shouted in class to her so she would stop copying. Lucky for her, the lecture let her go. After the test, she even dare to tell me she didnt copy at all and pretend all innocent and the guy who let her copy his work even scolded me why I made such a big fuss because I could get both of them into trouble. I WAS UP TO THE VERGE OF EXPLOSION. Immediately after that I walked out of the class and since then I never bother talking to them anymore, and I think they got the message. So from now on I have less one close coursemate and to be honest I don't have more than 5 close coursemate.

In another separate case, while I was attending one of my lecture, I was trying my vesy best to pay attention to the lecture, but this chinese girl kept talking non stop to her partner next to me and she just couldnt stop and lower down her volume. Eventually I couldnt take it anymore and I told her to keep her volume down. Although after that I enjoyed a moment of peace during the lecture but I felt guilty for being so mean to her so during the break I said sorry for asking her to tone down and she was nice enough to admit she was wrong and said sorry back in return. After a moment of reflection, I felt I am mean and bad, or just plain rude? Did I do the right or wrong thing?

All those actions mentioned above seems to be the right thing for me to do, but maybe I am a symphatetic person so my guilty consience kicks in really fast. I wanna be nice to everyone and a friendly person because I can't live without friends but am I chasing them away by being like this? Sigh. I really need advice on this. How to be a "Nice" Girl.