Perhaps as many have said that perhaps it is better to wait...till you are ready.

But if you are sincerely wishing to make it to your 50th--there will be a lot of situations and things happen in your marriage that would be equally and more so trying.

Perhaps placing a 3some in some sort of perspective balanced against life with all its wonderful special bliss, tradgic turn of events, and just your every day happenings, you can findout just how important or even unimportant this will be in your lives. The main issue is trust, if you can not trust yourself--or her at this stage, well.....then what?