mucked a winning hand tonight

sick to my stomach, flop two pair 2 5 clubs tight guy raised i knew he had over pair he kept betting big i called turn was a 9 clubs river was a jack of clubs he check river i saw him turn over pocket 9's for set that's all i was thinking about i slamed my two five clubs down into the muck not realizing the jack of clubs made a flush, lost a big pot but sick to my stomach that i didn't just turn my hand over 

Damn yo, use periods