I have a long-time friend that is dating a guy, but we don't want to invite them both since the gal isn't divorced from her husband. I'm afraid to lose her friendship, but my fiance & I will feel uncomfortable exchanging vows with - that situation - right there in the audience. We've discussed having a sit-down discussion about why they will not be invited, but I'm afraid this will just blow up in our faces. What would you do?