What should I do if I accidentally see menstruation cheating?

If you see it, you might as well ignore it. If you see it, spread it around and tell your uncle that it will only affect their impression of family harmony, and the relationship between your uncle and your aunt will also break down, and his family will also break down to the end, feeling that you are the culprit in destroying their family!

Because you saw him cheating, it doesn't mean he cheated for the first time, and it doesn't mean you didn't know. Sometimes some things are like this. He just doesn't know it, but his family is still a complete family. In front of outsiders, but what is Maruko's family, their affairs and internal affairs? They will get rid of themselves, at least the family has not broken up. You stabbed this layer of paper and their faces. It's not that you didn't face it, nor that you embarrassed their family! Finally, facing it may lead to the breakdown of the family.