<human>: Summarize the given text in a few sentences.

Basically I lied to my girlfriend about a girl that I occasionally talk to. She asked me if we had any history and for some reason I claimed we didn't, when in reality we had a short relationship. I think the reason was that it was easier to just say that than have her possibly get upset about me messaging an ex when in reality I have absolutely no romantic feelings for her any more, though I'm unsure how she feels about me, and have no interest at all in being anything other than a friend. 

Thing is now if I tell my girlfriend the truth, it will seem like I've been hiding this from her for a worse reason than is actually the case, and how I'd explain my actual reason. I know that obviously coming clean is a sensible option, but I'm worried about the impact that will have on our relationship. I've also thought I could stop talking to the ex completely as then there would be literally no chance of my girlfriend finding out (there are no common friends etc.), though obviously it's not the kindest thing to do to my ex. 

I'm just hoping for some advice on what I should do, any and all would be appreciated.
<bot>: Lied to my girlfriend for no real reason, not sure how to proceed, and what course of action is the best