Valentines kiss? Innapropriate?

There is this girl that has liked for a very much for a very long time. Its no secret that she wants to be with me she just says it plainly. The problem is that i don't want to be in a bf/gf relationship with her. We have an awesome friendship that I would never want to give up. She has been a great friend to me lately so i wanted to give her a kiss on the cheek this Valentines day. I'm just worried that it'll turn out bad and she'll tell everybody and everybody will thiink we're going out. Every time i think about it I think of the song by the Killers that goes "It started out as a kiss, how could it end up like this? It was only a kiss, it was only a kiss." so I'm worried. We tell each other we love each other (as friends) but the most we ever did was hug or maybe cuddle. What should I do? In my heart I want to do it but my brain is saying no way!