Just Quit My Job

I just put my letter of resignation on my boss' desk.  I don't know whether to be happy or cry.  I thought I'd feel better once I finally made the decision, but I don't.  Its short; really only two sentences: I'm resigning.  I've enjoyed working here and thank you for the experience.  He won't get it until this evening when he's back in the office.  I won't be back in the office until Tuesday.  There's a part of me that's hoping he won't accept it, that he'll change things so I'm happier here and that this time, the promises he's made before will really happen.  But, I'm guessing he's not going to say anything except that I don't have to stay for two weeks if I don't want to.  I feel like I've completely failed as an attorney and have let a lot of people down.