I feel for you, I really do. Shortly after my husband and I were married, I wanted to surprise him when he got home from work. I cleaned up the apartment until it shined and put on a maid's uniform with a tight bodice, wide, short skirt, fishnets, heels, etc. When he got home and I saw the door start to open, I pulled it open and said in my best French, "Welcome home sir, I hope you find everything to your liking". The building super was standing behind him - he had asked the super to come up and fix a broken light switch. They were both silent and then the super asked "what about that switch"? My husband laughed and said "if she missed any spots on the floor she does deserve that, doesn't she?" They both thought that was hysterical and the super never stopped smiling at me for all the years we lived there. If women were allowed in the Legion, I'd probably have joined with you.
Thank your lucky stars that at least you were clothed. Imagine if you had been waiting for him like that in some skimpy outfit!
I don't know about your in-laws, but I guess once I got beyond the awkwardness of seeing my daughter in-law tied up, I'd probably feel happy that my son's wife would be willing to do something like that for him. That's good in a relationship, though maybe not with company going through the door.