IS IT OKAY TO UNINVITE SOMEONE FROM SOMETHING?!

Okay so there's this guy I work with that I had a big crush on for a while and it just recently faded out. I asked him to go to my formal with me and he said he would love to. This was a couple weeks back when I still had a huge crush on him and now I don't and I hate myself for inviting him. WTF DO I DO BECAUSE I REALLY WANNA BRING MY GAY BEST FRIEND INSTEAD AND I KNEW I JUST SHOULD HAVE DONE THAT FROM THE BEGINNING. I'm just so upset and wanna cry because I'm taking him. Like I'm pissed at myself. I don't want this guy going with me. Has anyone ever uninvited someone from something and got away with it?? Please fucking help me. I'm depressed because of this and my formal is on March 11th...