What should I do if I have a vicious sister-in-law? Is it true that the people who stir up trouble all day long are just waiting for the end?

First figure out why he is targeting you so much. There must be something you haven't done well in some aspect or something he doesn't like, which will make him snitch. It doesn't hurt. Ask him clearly what you are doing. What annoys him, be broad-minded, don't be a petty person, give in as much as you can, be nice to him, let him know that you are not what he imagined, and as time goes by, I believe he will treat you better. Your views will change. After all, people’s hearts are not made of stone~~