I got really nervous and started rambling on like a complete idiot and walked away?

So I have a girlfriend but there's this girl in class I think is kind of cute but I choked up while talking to her. I couldn't control what was coming out of my mouth, my heart was beating way too fast, and I was talking wayyy too fast and I embarrasd myself and just walked away without saying anything. Usually I am totally chill I have no idea why this happened is it because I feel bad that I think she's cute? I feel depressed because I embarrasd myself too much...She looked at me like I was retarded.