In most families, the relationship between daughter-in-law and mother-in-law is far from ideal, especially when women live in the same territory.
Even if the mother-in-law causes only negative emotions, you need to treat this woman with respect, because it was she who gave birth to and raised your chosen one. Often, even unconsciously, a young wife uses phrases that can completely ruin the relationship with her husband's mother.
“We'll figure it out ourselves” is an expression that the daughter-in-law often uses. And this applies to everything: shopping for food, choosing a place to stay, raising children, etc. In such a situation, it is enough to listen to the second mother, thank for the advice and do it your own way, the conflict will end before it even starts. However, it is worth considering: maybe the mother-in-law is right, because she has richer life experience and experience of past years.
“You raised a mama's boy” is another frequently used phrase. All people have flaws, including your husband. To accuse the mother-in-law of the fact that she raised her son incorrectly is at least stupid, and no one forcibly dragged him down the aisle.
"You owe me (should be grateful) for living with your son." Such phrases are usually heard in those families where the husband has not reached certain heights, does not earn much, may have a glass or two, does not help around the house, etc. Here the question naturally arises: who forced to marry this loser, certainly not the mother-in-law …
“But my ex …” For every mother, her child is the best, smartest, unique, talented, etc. and comparing the previous man with the real husband in the presence of the mother-in-law is, at least, stupid. And it is not at all necessary to tell her about past relationships.
To improve relations with the mother-in-law, you need to ask as often as possible what the husband was like in childhood, what he liked or what kind of sport he did, what he ate and what time he went to bed, you can ask to show his childhood photos and crafts. Moving in this direction, you can get a reliable ally in the person of the mother-in-law.