What do you do when you feel so disheartened?!!?!?

Seriously, what is a girl to do!?!? I've never felt so disheartened before, I don't understand what is wrong, what is right. I feel like giving up! Up until this day after being at university of Hertfordshire I have never even missed a day beside when I was seriously ill and throwing up for a week during second year and I've never even been late. I get into uni early and stay late at times and work a home a lot! I try so hard and put so much time and effort but seriously what in the world does it count for ?!!?!?! When I know that there are people who don't even put time in, kinda probably doesn't care that much and just stroll in when they feel like it, some of them seem to do better than me! Is the world really that unfair or do I just suck!?!? I actually can't understand and I m sick of it all really! I worry because I care, I stress because I want to do well and I cry because it means a lot to do well and care about my degree but I put so much time , thought and energy into my work but it doesn't seem to be worth for anything other than a mere 47 = D1, to me that is simply not good enough! So what exactly to do, because I m trying my best and working so hard but seriously it is sucking the life out of me! So can anyone answer me? what should I do ?!?