For better or worse, in-laws come with marriage. Even the most well-intentioned mother-in-law can begin to feel like an unwanted guest if she continually drops by without warning, and it can be difficult to find an appropriate and polite way to tell her that you would rather she didn't drop by unannounced. As Dr. Phil advises: "Good fences make good neighbors. Your in-laws need to be your neighbors and there need to be really good fences up. Set boundaries about when they are and are not invited into your lives."
Tell your spouse what is going on in a calm and straightforward conversation. Be clear on what you see as the purpose of the conversation, even if it is to just vent. You do not have to problem-solve immediately, but you do need to keep open the lines of communication.
Decide, together with your spouse, what is in your best interests as a family, and get on the same page to create a united plan. You may want to discuss if speaking to her as a couple, or your spouse having a one-on-one conversation with her would be most effective. Come up with solutions that aren't prohibitive on your in-laws, but create appropriate distance and space.
Speak with your mother-in-law. When you do talk with your mother-in-law, be understanding and appreciative of her role in your life. As psychologist Dr. Marie Hartwell-Walker advises, "When you have this conversation, it’s important that you stay loving and clear, not angry."
Enforce your boundaries. If your mother-in-law drops by unannounced, either ignore the knocking at the door or answer, but politely refuse to invite her in. Consider saying, "It's so nice you stopped by, but I'm busy and unable to entertain a guest. How about we set up a better time to visit?" Suggesting an alternate day to spend time together hopefully will help her remember the boundaries you've set and work on respecting them in the future.
Show respect and patience. It may take awhile for your mother-in-law to recognize the boundaries you've set, but that doesn't mean you should stop showing her respect. Act like the daughter- or son-in-law you'd like to have, if the situation were reversed.