I've been in a situation like yours once. I was really upset and didn't know what to do. By that time I was reading a Derek Sivers's book Anything you Want and

I've been in a situation like yours once. I was really upset and didn't know what to do. By that time I was reading a Derek Sivers's book Anything you Want and I was feeling so much connected with the author that I've decided to send him an e-mail telling my story and asking for some advice/guidance. For my surprise, he replied my e-mail on the next day. I think his answer fits to your question, and by the way, it was exactly what I did and it couldn't have been better. Mr. Sivers's answer: "Quit now. If your heart's not in it, get out. Be honest with [...]. You're not helping them or your self by doing something you're not excited about. :-)" Don't be afraid to quit.