What should I do if I find my mother-in-law cheating?

hey! I'm similar to yours. I also found out that my mother-in-law was cheating on me, but I didn't expect that under my father-in-law's nose, my mother-in-law was a very smart person, who looked young and loved to dress up. I really hate such a self-righteous woman, who obviously is a pile of things, but also picked on others left and right, sometimes I really couldn't help but want to expose her and was afraid of causing a tragedy.