I agree with the advice that you have already been given, and I want to emphasize that it is CRITICAL that you communicate. If you are still in a place where you can speak to your Mom, do so regularly. Speak with your Dad as well. But do so without placing blame. It is OK to feel angry or hurt about the situation, but realize that it is likely not YOUR fault that the situation exists. If you were separated because your parents separated, realize that they were doing what was best for them, and while it may hurt you now. it has nothing to DO with you, really. If you can keep things in perspective, it will make it MUCH easier foe you to communicate openly and honestly. When you do speak with your parents about the situation, be careful of your phrasing - saying "I am feeling hurt" is MUCH better than saying "You hurt me" for it focuses attention on how you are feeling without starting a blame game.
Aside from your parents, do keep open lines of communication with teachers, friends you trust, and even the guidance counselor at your school. Also, WRITE!! When you feel the most stressed, instead of blowing up at someone, write about it. Then, put it away for 24hrs and come back and reread what you wrote. Sometimes, that distance alone is enough to help you put it all into a better perspective.