This article might be of some help: http://www.teenconnection.org/issues/divorce.htm
Or you can check your local listings for a teen-oriented support group.
First of all, it's okay to be scared. My parents divorced when I was much younger, so I can imagine that this is impacting you much harder than it did me. Remember that nothing has happened beyond your present situation. Things may get worse or they may get better. It depends on the people (your parents) involved and the situation that has occured. However, it is always traumatic for children to see or hear their parents fighting, and there is nothing wrong with this upsetting you.
Unfortunately, there is not a lot you can really *do* - the situation will change over time on its own. The best thing you can do is take care of yourself and express your feelings (if you have another adult you can talk to comfortably, possibly a family member, friend or professional counsellor, I suggest you contact that person when you need to vent. There's no harm in venting, and it will relieve a lot of the pressure that builds up from stress :3). If at any time you feel a certain way about your parents that you think is wrong to feel, it's OKAY. You have a right to your emotions, and if you are angry, afraid, or resentful, it is not your fault for feeling that way. Talking to someone you trust, such as a close friend, is okay too. There is nothing to be ashamed about when it comes to your parents having trouble. All couples do, just some more than others.
I encourage you to continue to seek support on this site and other resources as well. And no matter what happens, trust that life will work itself out. You will be okay. :3