Mother-in-law incest: The melancholy of a very lewd mother-in-law

A few years ago, I married an older man. He is what the world calls a middle-aged person. I have lived my life without any inconvenience, but there is one problem. Maybe it's because my husband is getting older, but he gets weaker at night every year, and even though we only have sex a few times a month, he ends up feeling good for himself. Unfortunately, I feel like my sexual desire is getting stronger every year, and my frustration is only increasing... One day, as a joke, I tried to play a prank on my son-in-law, Ken.