Am I being a bi**h by not letting my friend look at my college work?

Feel no guilt at all. What she is asking is wrong. If there was no 2nd bite at the apple with the class and she was confused, I might say help her out. She has had how long to figure out what she didn't understand and even had a Cancer to go hear a more simplified or clarified lecture... Sleep easy, no ***** about it! You are working hard, why give your work to someone else who is slacking off? There is a difference between help and blatant copying of your work. Good for you for being a good student. Karma will more than likely get HER for asking you to put your education in jeopardy.