Kyle Richards -- I Bitched Out ... When Lisa Rinna Attacked My Sister

Kyle Richards cops to being a total coward when the now-legendary fight between Kim Richards and Lisa Rinna broke out -- and that's because she says it was 100% legit ... shattered glass and all.

The "Real Housewives" star was leaving Mr. Chow when she told our photog the brawl was NOT fake drama ... despite speculation it was all choreographed.

Kyle explained why she ran for the hills -- instead of jumping to her sister's aid -- which led us to the most important question: Could she take Lisa in a fight?

Place your wagers ... then watch the clip.