I’m wondering if you also get agitated around other high energy people or just your mother-in-law. Taking some time to reflect on this might also help you know how best to respond. It’s one thing to be sensitive to all loud, gesticulating communicators and another if you really only feel drained after interacting with your mother-in-law. Either way, staying calm will be key.
Try mentally preparing as much as possible before the interaction. If she gets loud, keep your voice at a low volume. If she speaks faster, keep a steady pace yourself. Focus on listening to the content of what she is saying rather than trying to take in all the extra movements and tones. Finally, with her in particular, I would speak to her about the differences in your communication styles and see if you can find ways to meet in the middle.
In general, it can also be helpful to use imagery and metaphor to keep your energy separate from others. You can imagine that you are surrounded by a bubble of light, that a window is between you and the other person, or imagine a mirror between you and the speaker with the mirror facing toward them. It can also be helpful to ground yourself before and after the interaction. There are many ways to do this but saying a mantra or prayer and taking a deep cleansing breath are great techniques. You might also benefit from taking a class on communication, or even meditation or yoga. Hope these suggestions help.
All the best,
Dr. Holly Counts