Embarrassed husband sees wife's friend naked...and they fuck

My friend came to stay. As we head through to say goodnight, we walk in on her naked. Poor hubby didn't know where to look and felt so embarrassed. He has always thought that she is cute but it was really awkward. She was great about it and not shy at all. I thought that the whole thing was hilarious. Between us, somehow, we turned the whole situation into a cuckquean/swingers thing and he ended up fucking her friend in front of me. He is a little less embarrassing now I bet he is still picturing her naked!