​As you and others have suggested, there are two parts to one's response - what you say to yourself, and what you say to the dancers. I think the latter is more important, and it is of course affected by what you say to yourself. Being able to respond humorously, recognizing that like everyone else you make mistakes, apologize for them and then move on is very useful. What has bugged me most about callers are those who get angry at the dancers (some of whom may be slow to understand the nuances of what a caller says, although usually it goes back to the caller's instructions) or visibly at themselves. Who wants to spend time with a person who is preoccupied with being angry at you or themselves for being human? 

To the extent possible it can be useful to switch into a problem-solving focus. During the dance you want to figure out quickly what went wrong and/or what can be done to salvage it - make a correction, stop and start over, switch to a different dance... After the dance is over there is time for the post mortem, which seems to be what you are concerned about - what did I do wrong, what could I have done differently? Focusing on how terrible and inept you are takes away from problem-solving - you can't change what has already happened. Of course I admit that this is easier as one gets older (and has more mistakes to put into perspective). If it helps perhaps you could keep a catalog of the mistakes made by all the callers you respect. You're in good company!

David​