getting married need advice

I'm getting married at the end of the year to a woman I love so much. We've been together for 5yrs. I without doubt want to spend the rest of my life with this woman and I have never cheated once on her or any other woman ever, but I've been placed in an interesting position and don't know what to do.

There is a woman who I have known for 20yrs. She has been a very good friend of mine and for many years, I have been crazy about her. If the timing were ever right, I would have wanted to be with her. She was always with someone and I was always afriad to tell her how I felt. Time has moved on, and I am with the woman I want to be with, but I think my longtime friend might have a thing for me. Regardless, I will not leave my soon to be wife, but I am in total aggony because all I want to do is kiss my friend. I want to share a really good kiss. Just so I know, and just so I can move on because I am kind of unsettled on the inside. I know she will kisss me back and regardless if it is amazing, I want to be with my fiance, but I just can't live the rest of my life without that kiss. She is the girl that got away I want to live my life without regret.

So, do I kiss her, get it over with and move on, and live with the fact that I kissed another woman (before I got married). Or do I not kiss her and wonder for the rest of my life what it would have been like and drive myself crazy?