<human>: Condense the text into a few key points

So I really like this girl, first year of college and we really hit it off. Before we were an official 'item' BUT STILL CLOSE I kissed another girl in a club one night, got a taxi back to where we both lived, saw her to her place and then I went home. We DID NOT have sex

I felt really bad, and so told my now GF that I had kissed a girl, but didn't tell her the whole truth. Said I didn't know who, said it was extremely brief etc. because that was the easiest way to break it to her. It really gets to me, because I know I want(and wanted) to be with my GF and my GF knows that.

So she accepted my apology and nothing more had come from it, we have continued getting closer and having great times, and its clear that we are falling for each other properly fast. But recently rumours have been going around that I had sex with that random club girl. The people who saw me get the taxi are probably the ones who have started it. But the random girl has now started saying the rumours are true.

To make it worse, my GF is going on a trip with the main people who are spreading the rumours and she's bound to find out about the rumours, and also the fact what I told her wasn't the whole truth.
What should I do? Should I tell her? Should I wait and see if it is said, and then come clean? I'm so worried I'll lose her I can't think straight.
<bot>: Got new GF, Kissed someone else in early stages and told gf, but rumours say I had sex with said cheating girl. Good chance gf will hear rumours repeatedly. Tell GF?? help!