(She has a boyfriend, but I don't think he treats her very well.)
Doesn't matter not one bit, as its not your business. What is your business is how you treat your friend with respect, and not cross the boundaries of good behavior. You want to keep her as a friend, keep your feelings to yourself and forget the romantic notions stirring in your head.
I don't love her but that doesn't mean I couldn't
You had fun at your reunion, so respect her relationship, and keep your dignity, and distance. Why cause a problem where there is none yet.
Booze, and a kiss with a nice female, has you wacky my friend, and she wasn't going to sleep with you any way, just talk, but your kissing her told her its time for you to go. Don't let your inexperience or ignorance in the ways of woman have you doing something stupid to mess up the friendship, or foolishly make things awkward, by confessing feelings you admit you don't have. Let it go and enjoy your memories.
No need to be stuck on them.