BTW a triad is a relationship where everyone is involved with each other. A "V" is one where there is a central person involved with 2 people who are not involved with each other. Hope that helps a bit with the terminology.
I agree that bringing this up face to face is probably the way to go. I would start out by saying that you don't need an answer right away and that you don't want the discussion to make things weird between the 3 of you. Good luck.
Everything will be ok in the end. If it's not ok it's not the end.