Dead with guilt

I am feeling so low today. Have a maths test tomorrow but don;t even feel like touching the book. It hurts us a lot when we realize that we have hurt a friend. And that's what I did today. Ruined almost everything. Not intentionally though. But did something very stupid. Idiotic. Curse of a big fat mouth. Just talked to her now. Of course she is sad and yet she says that she doesn't blame me and I should stop worrying, but how can you stop thinking when you know, despite what others say, you are the only one to blame. It was my stupidity that is causing all these troubles. How can i stay calm after knowing all these. And the guilt increase all the more when she tells me that I am not the one to be blamed.  :(  Dunno if I can forgive myself for this. Just hope that this friend of mine gets out of all the trouble that I put her in. And I got to do something with this mouth. A bad talking habit. Useless talking. Annoying talks. No more of these. :X