A good friend of mine has the personal policy of giving herself 24 hours to spend feeling bad about a disappointing experience. Which makes sense for a few reasons.
1. You have a chance to acknowledge the fact that something bad happened
2. You have plenty of time to really feel sad
3. By the end of 24 hours you are usually sick of feeling bad, and don't feel like you are supressing your feelings by moving forward.
Once in a while there is something that happens that is so difficult that you really do want to wallow for longer. But having a definite end point arranged is best, that way you can say with authority: ENOUGH is ENOUGH. And you are controlling your feelings instead of allowing them to control you.
So I've reached the point where I am over it, and since I've already ordered the score and a recording, I'm going to learn the whole role any way. The minute it comes, I will dive in as if I do in fact have to sing it very soon, I'll get my translating on and get to work. I just know I'll sing it, and when the opportunity comes, I'll be ready.
And in the meantime, and after work of course, you'll find me at the pool.