Did i ruin our relationship?

Last Friday night my mom was out of town an so o course I had friends over including my best friend of 8 years. Well we were all drinking having a good time talking, laughing ,life couldn't get better. Everyone leaves expect my best friend who was Completly drunk so she passed out on the couch being the nice guy I was I woke her an invited her to my bed ( we have slept in the same bed before so it was no big deal) well things kind of went far next thing I know she is on top of me an we had sex probably the best sex I ever had. I wouldn't have thought this would happen in a million years because we just were never like that it was more like a little sis big bro relationship. If your reading this your probably asking yourself what is the problem two best friends finally fell for each other after these years, well your wrong I'm the only one who did an today I finally worked up enough courage an asked her to give us a shot an she turned me down. I never had feelings for her before that night an idk why I have them for her now. I'm heart broken that not only did I think I found the perfect girl that was under my nose the whole time but now I think I lost my best friend Pursuing this fantasy of a non realistic relationship. I don't care if we never become a couple I just hope I didn't lose probably the most important person in my life