It's understandable that your husband doesn't want to get caught in between but doesn't he feel his mother is being unfair and he needs to set the record straight? A spouse can support you and acknowledge that his parents are being unfair but what about taking a stand because it's the right thing to do? I personally would be very upset if my parents think bad of my spouse and will make it a point to clear up their misconceptions because it matters to me that they like him and respect him. It will definitely hurt me if they think he is not a good person or is fake. It just creates unnecessary drama.
I guess in my opinion, it's not about being supportive behind closed doors....it's about taking a stand for what's fair and right and based on what you've said, your MIL is definitely not being fair to you.
His mother will never ever say she is wrong .. EVER even when she knows herself that she is wrong. That's just how she is. She is nice but doesn't want to hear that she is wrong. She takes care of us... cooks for us.. shops for us .. as long as well agree with her we are all happy. My husband knows that she was wrong in all this and he even tried to tell her that don't involve my wife in this mess. Did she listen.. ummm no.. she started crying and started telling how much she has done for him and his life, which actually is true. But looking at her, my husband gave up and said sorry to her. He also told me that he knows his mom is wrong but there is no way he can reason with her so I have to be the greater person and just forgive and forget.
And as far as living with them like this forever, my in laws are VERY old and Very sick so hate saying it... they really don't have a very long life.. I hope they do but looking at their health its best to make their last few years comfortable and listen to few things they have to say.
My only point was to win her heart and show her that I am not as bad as she thinks.
I think whatever you are doing is what you should continue doing. Stay out of anything between your husband and his parents. And continue to be nice, especially since they are very old and sick. Simply put, you don't wanna deal with your or your husband's regret or guilt once they pass because that's irreversible.
Sure it's not idealistic and we can write essays about the pros and cons of a person or a situation but it's always difficult to find one choice which can be called righteous, feasible, and ideal simultaneously. And some people just don't bend- they either like to have their own way or when confronted they raise hell for everyone. You just have to circumvent such people rather than be the brave righteous warrior and face them head on especially when they've passed their years of vigor but are trying to hold on to it by way of their age/relationship. Pick your battles, your husband is doing the same. It pricks the ego and hurts feelings but with some people you just can win.
In other words, continue being calm. Don't get instigated by the posts here.
And if the spouse supports you before his parents.............again it will be said that the wifey has brainwashed him. Would it be so wrong if the wife herself was to discuss matters more directly.
I remember seeing my mom address both her MIL and FIL together....about issues (where it was clear they were in the wrong) but she didn't do it in a way that was disrespectful. Her voice was calm...she stuck to the facts. And while it may not have brought about a dramatic change in their feelings (at least not right away)...it seemed as though some of the negative behavior had calmed a bit. My dadi was in general nice toward my mom....but there was a time when (just like the OP's MIL) she blamed my mom for something that my mom had NO IDEA about. My dad had made a decision about a matter.....and it was not known to my mom....my grandparents were not happy about dad's decision so they thought that my mom was the one behind it. That was a challenging time period....but usually the relationship was cordial.
A few years down the road...my dadi became even nicer to my mom. Perhaps the death of my grandfather brough about that change. Maybe it was age. Or maybe it could even be her reflection of her past behavior and my mom's response that could have made her realize her errors.
Who knows. I don't think it's the worst thing in the world for a DIL to confront in-laws for REPEATED rude behavior. Again, it can be done in a respectable manner. But the OP would have a better idea as to what strategy would work with her in-laws. Whatever she decides, I hope the situation improves for all parties.