The fantasy pales in comparison to the real thing. We started with threesomes but have now discovered private interracial parties. If she's agreeable ... find one, sign up for it ... and go! These parties carry no obligation but trust me, once you're there it'll happen if you let it.
It's also relatively safe compared to meeting individuals who you don't know and whom haven't been screened. You have to be a bit careful at a party too but at least there are plenty of other people there. Your white wife will be the center of attention! LOL