@BILS
You still were not clear :)
Did you and your wife play with that woman or is it that you have swung before? Two different interpretations there.
Do you feel that your friend is offering up an encounter with you and your wife? If so, that is a whole can of worms that you have to make a decision on.
Let me assume that is the case. You and your wife are friends with this other couple. They want to fuck you guys. This happened to us. We had been in the lifestyle for half a dozen years and our accountants were just getting into it. It took a HUGE amount of balls for them to talk to us about it. We were in our 30s, they were a dozen years older. We were such good friends that we went to their kids Bar and Bat Mitzvah. We were identified by one of their kids as being influential to them at the Bar Mitzvah. We chose to say no. Our logic was simple: The friendship was worth more than risking the friendship by exchanging bodily fluids. Now, that we are older, if we had some vanilla friends that were +/- 7 years of us, chances are we would say yes. We feel that we are more mature now in how to handle the situation should it get wonky and we feel that because of their age, they could be mature and wise enough as well.
But it also goes back to a statement that I used to make about affairs. Sixty minutes of pleasure is not worth 60 years of hell. So if we had any inclination that it would destroy the friendship, we would pass. Sex is easy to find, friends are harder to come by.