Confused from the south

My husband and I have been together for 35 years and he has convinced himself that he wants to watch me have sex with another man. He says the thought turns him on. He recently admitted that he doesn't think he would ever let me do it however I wonder. I am bothered because I know it will only cause problems in the end. He watches porn and says he is watching the big dick fuck and it makes him horny. He stays at his office late to do this and it bothers me. How do I handle this ? Do I learn to let it go and play along, and get over the porn issue.