Summarize the following:
If your mother-in-law has always been critical, demanding, or argumentative, you may need to simply work out a strategy to minimize the behavior and cope with it. If this is a new behavior and it is directed only at you, there is likely an underlying problem that must be addressed. Talk to your spouse to get a better understanding of your mother-in-law. If you’re nervous about broaching the subject, say something like, “I’d like to talk about the way your mother has been acting, but I don’t want to fight. I just want to discuss the issue to see if we can find a solution.” Presenting a united front with your spouse will send the message to your mother-in-law that her behavior is unacceptable. If your spouse confronts the problem first, it will signal that you both acknowledge the issue. Ask your partner to talk to her privately to see if they can uncover the root of the problem. If your spouse is uncomfortable getting in the middle of things, ask them to at least stand up for you when she crosses a line.  Ask your spouse to report back to you after they have a private conversation with their mother. They may have some important information about what the root of the problem is. Tell your spouse, “I really think that you’ll have an easier time talking to her than I will. If you talk to her first and figure out why she’s not acting fairly, it will make it easier for me to sit down with her.” Don’t get ahead of yourself and start talking or arguing with your mother-in-law without consulting your spouse first. If you cross a line or engage in an argument without agreeing on a coping strategy, you may end up offending your spouse. Decide on whether you want to confront, deflect, or avoid the problem together to give yourself the highest chance of succeeding. Even if you want to deal with the problem by talking to your mother-in-law privately, you should still consult your partner first. They may have some tips or advice on how to speak with her, and you should give them a head’s up in case your mother-in-law goes to consult them after the two of you speak.

Summary:
Talk to your spouse to see if this has always been a problem. Ask your spouse to back you up or talk to her if she’s only focusing on you. Develop a strategy together to solve the problem.