I notice that there are so many threads about dealing with difficult MIL's. It is an age old problem that so many DIL's can relate to.
My MIL in favors me over her other DIL. This is likely because I did not "steal" her favorite son from her-my husband's brother is her golden child. It could also be that I interact with my mother-in-law in a manner which is respectful and loving. Unlike my SIL, I do not mock my MIL or look for reasons to be upset. While I sympathize with my SIL, I think she can be oversensitive and rude to my MIL.
My MIL is a matriarchal type who is also jealous of her son's wives. She did not receive the attention or doting that her DIL's did and this makes my MIL angry. I will share what worked for me and hopefully it can help the DIL's out:
1.) Remember that your MIL raised a good man for you. She can't be all bad if she raised such a nice son.
2.) Be respectful when interacting with your MIL. Even when she is rude, be magnanimous and polite. Refrain from sinking to her level if she is swearing or shouting.
3.) Let your husband handle any problems you have with his mother. Blood talks to blood and he knows the best way to discuss issues with his mom.
4.) Do not constantly torment your husband with every little thing his mom does wrong. It gets annoying and it is much better to pick your fights-let some things go and keep the serious discussions for huge issues.
5.) Always be a united front with your husband. No talking about personal marriage problems with either set of parents. Support each other when handling in-law problems.
6.) If parents are too meddling and cantankerous, keep them at an arm's length. At the same time, try to understand that they no longer feel as needed in their adult child's life and the meddlesome behaviour is compensating for that loss.
7.) If the relationship is civil, try to reach out to your MIL. I call mine without having my husband around and we shoot the breeze. My MIL greatly appreciates my warmth and she brags about how what a "wonderful girl" I am.

That woman never lets one of my birthday's pass without a nice card. She has sent care packages as well.
I realize that these tips are much easier said than done. I am not saying that this is the only or best way to handle MIL's...once again, I am just offering my opinion.