Help, married but have chemistry with colleague.?

I am married with a lovely wife and two lovely kids and thought i had everything, now my head is all over the place. I have suddenly got a major issue with a colleague at work. We have been working together for about 6 months and have got on well from the start. There has always been some chemistry between us, but as we both have partners and are happy with them, i thought nothing of it, then last week we were talking about stuff and the old "if you had a freebie, no guilt, no strings shag" discussion came up and we both said it would be tempting. Anyway that lead on to the realisation that we both did like each other and the chemistry exploded.......but we havent done anything. We went away and thought about it and both came to the conclusion that we would not only hurt our immediate partners, but also the kids, family & also the fact we work together. Luckily i now have a holiday so we wont be tempted for another 10 days at least. How do we move on safely? aaaaaaaand breathe..