Okay, I finally explained myself properly to my friend.
Explained that I'd been having these confusing feelings for her, and when I was drunk it got the better off me. Explained it all, told her I won't drink around her in future because I don't want her not to come out with me, and I think we're more or less all good now
I certainly feel much better. Hopefully I can finally get a goodnight's sleep now!
Cheers for the help people. I'll look at the drinking issue.