chagrin
A feeling of embarrassed disappointment and annoyance with yourself.
Chagrin is the feeling of embarrassment mixed with frustration or annoyance, especially when something doesn't go the way you hoped. If you confidently raise your hand to answer a question and then realize mid-sentence that you're completely wrong, that sinking feeling in your stomach is chagrin. It's worse than simple embarrassment because you also feel irritated with yourself.
Imagine spending hours preparing a science fair presentation, only to discover you've been pronouncing the key term wrong the entire time. Or picture yourself bragging about winning a race, then finishing last. That combination of feeling foolish and annoyed is chagrin.
The word often appears in the phrase “much to my chagrin,” which means “unfortunately for me” or “to my disappointment and embarrassment.” A student might say, “Much to my chagrin, I forgot my lunch on the day we were having pizza.” The phrase suggests you're looking back at something that didn't go well and can almost laugh at yourself, even though it still stings.