My Wife Gives More Than Piano Lessons

I have been happily married to my pretty wife for more than 30 years now, we have had children that have left the nest. I bought my wife a fancy baby grand piano because she is a great piano player, and she was bored. She decided to start giving piano lessons as a side hobby and for some extra spending money. I thought it was great, and everything was going well until I noticed her paying extra attention and time with a young man that was her favorite student. She was seeing him several times a week in our home in private. I decided to put in a stealth tape recorder in our bedroom on a hunch. It paid off well. I listened to them making passionate love to each other in our own bed and our bedroom! He must have a magnificent cock from the sounds of it, and her frequent orgasms. I heard "Fuck me deeper", "You are so big!" and "I'm cumming" over and over again. It got me so hard I jerked off a massive load of my own cum just listening to them!
It turns me on that my wife is a "Hot wife", and I want her to continue to have great sex with her students. My tape recorder is ready, and I may figure out a way to get a video recording of them. I find it to be very sexually stimulating. I am also buying some sexy, lacy panties, lingerie and nighties for my wife to wear in front of him in the bedroom. I am sure she will use it to keep him stimulated. I just hope he does not impregnate her. She has a diaphragm to use for now.