I think that you are being incredibly unselfish in your desire to get her motor running again.
I would caution you to be very connected with your husband if you go this route. But - we are uncomfortable with swinging alone, so take our advice with a grain of salt. We feel that partners playing alone can lead to too many emotions.
Other than that little caveat, I'd say it is a really kind thing to do to help her restart her libido/vaginal juices... The drying up of vaginal juices is sincerely one of the saddest things that can happen in the world
Spoomonkey