I believe I can understand where your W may be coming from on the "how you talk to her part". Here's why....I grew up in a home w/a Dad who constantly sounded very condescending to both my mother and I. Our opinions didn't matter, his way was the only way to do things...he was the authority on EVERYTHING. It wasn't WHAT he said to us, it was HOW he said it....it was that tone of voice, that "my GOD can you really be that stupid!", or very patronizing, scolding type of a voice. Now, please don't think I'm saying this is what you are doing....but now, if my H uses a similar tone of voice w/me I can turn into a "B" instantly!!! My hackles go up and I'm ready to attack!!! Which is not my normal persona LOL.
I've seen my mother endure this behavior for well, my entire life. I've even brought this behavior to my father's attention...but he doesn't change it...much, for short periods of time he will, when I bring it to his attention...but it's never permanent.
So....IF you were doing anything similar to this, it's hurtful, degrading, demeaning etc. It might take her some time to believe that the change in your behavior is a permanent change.
I've even experienced my LDH talking to me in a similar manner once in awhile...naturally this gets my hackles up and between my being angry at being talked down to and him not understanding why I blew up at something he said...we could go round and round. I have now since explained to him that I have a bit of a Pavlovian response to a certain "tone" of voice that he sometimes would use w/me and explained why I would sometimes react in a knee-jerk reaction to him. He is MUCH better now about being aware and tries very hard not to speak to me in a patronizing manner.
I also noticed that your W just doesn't seem to really understand that there is a BIG problem (at least in your POV) w/your M. She thinks everything is hunky dory....so did my H, he was blind to the problems too....I tried EVERYTHING to get through to him....but you know what worked? Telling him that if we didn't seek counseling we wouldn't be having another anniversary...and meaning it.
He even stated in our session just last week that when I said that to him....he knew we must have a BIG problem and began to really take me seriously. Have you at this point set any boundaries w/consequences...or have you tried talking to her but really haven't set any consequences yet which might provoke her to take you seriously and really look at your R w/you?
Can you give us some examples of approaches have you taken? When you've tried talking to her what have you said...just some examples.
Sorry, this was so long-winded...had a bunch to throw in there