Louisouis, I am hearing you and feeling your pain. I have my own MIL issues. The unfortunate thing is that you will NEVER change your MIL but perhaps you can manage how you react to her and minimise the impact on your relationship with your husband. For me the critical difference has been the support my husband has shown me, and although his mother's erstwhile behaviour continues unabated, I feel better that we are 'in this together' more than previously, when I felt I was battling both him and my MIL.
I think the critical change (husband severing the umbilical cord connecting him to his mother) for me came in several stages but mainly after some issues related to my DD.
Initially my in laws had keys to my home (not too strange, my mom, sister and neighbour have keys to my home back in Australia for emergency use only -they have NEVER accessed my home in over 10 years since I've had my own place) however my MIL had a tendency to pop in all the time unannounced. Despite dark looks from me, a lack of enthusiasm for her presence and no hospitality extended to her (no drinks offered, not invited to sit down) this continued as clearly her hide is thicker than a rhinos and she didn't seem to get the multiple hints thrown in her direction. One time I was padding about in a long singlet top only (it was baking hot in HK), and my in laws came wandering around. Although I was embarrassed and beat a hasty retreat into the bedroom, they just stayed in our home milling about. When I didn't come out, my husband came to find me as he expected that I would 'get dressed' and come out. I told my husband that it was late (10pm or so), I was tired, I'm in my own home (I hope and this home wasn't an extension of my in-laws home) and if he'd like I'll come out dressed as I am. Needless to say, he quickly told them he was tired and had to work the next day, and hurried them off. After they left, he and I had a talk, about how a person should be able to be comfortable in their own home without having to be surprised by an unexpected person wandering into your home (we have helpers but they leave at 9.00pm sharp to their own quarters which is separate from the main home), and how would he feel if my sister or mother came wandering in on a regular basis when he was lounging about in his undies. He thought it was a fair point, and I suggested to him that as we were having renovations, we should change the locks and not give them a key. It took some time for him to agree, and we do have one those special locks where the key is complicated and takes some organising to replicate, so it was not too much of a stretch for him to tell his parents that it was easier for them to ring the doorbell as we have maids in house at all times (rather than 'I'm not going to give you a key to my home' which he wouldn’t have accepted as it would have been offensive to his parents). That made a huge difference to how I felt in my own home. Of course I have friends married to local men who can not do the same thing, as the in laws own their homes so feel entitled to enter and leave at will but that is a whole other post.
The second thing that happened was that I pointed out to my hubby that although for the most part his parents agendas and ours were aligned, at times, they would diverge and that I needed him to see and understand that. After the agenda observation, I would point out to my husband glaring examples of where his parents would act in their best interest at the expense of ours. I reassured my hubby that I didn’t believe that his parents were doing anything in a malicious way, but that it was about their own self gratification, and our unhappiness was just collateral damage. For example, recently my DD was requesting to eat her dinner in front of the television and threw some major hissy fits when I said no and held firm. My husband has also had to deal with these battle of the wills melt downs too, and I think that’s important, in how this played out long term.
Anyway, I’d no idea at all why she was asking for this when she’d always been fed at the dining table. I just figured it was a phase she must have been going through. Just 3 days ago I went by to my MIL’s home to say drop off my DD school bag (the helper had forgotten to give it to my MIL who has my DD 2 days a week) and of course what do I see but my DD in front of the telly with the full lunch spread, steamed fish platter, stir fried greens, rice, soup, a helper to feed her and her favourite Hi-5 video on whilst my MIL was chatting on the mobile and looking indulgently on. I waited for her to get off the phone and remarked firmly that I don’t want my DD fed in front of the telly, to which she replied that it was what my DD wanted. I told her 3 year olds don’t call the shots and just left it at that. I told my husband about it. Given that he has been tasked several times with managing my DD’s tantrum and tears over the dining table issue (mainly her screaming in his ear and rolling about on the floor), he was not impressed and had a very stern word with his mother.
Second example, my DD starts her night ‘run’ at 5.30pm. She has her tea, then her bath, then a 1 hour wind down with us, then 2 books and then sleeps at 8pm. When she is given too many snacks or too much sugar close to tea time or is returned home too late, she refuses her dinner, is agitated, refuses her bath, carries on in an irritable fashion and is generally exhausting. These sorts of days she won’t sleep until 12am, and of course my husband’s evening peace is interrupted (our helpers do not care for our children in the evening after 9pm) and he really feels it. These sorts of evenings always occur when our DD has been with the in laws for the day (consistently). My husband will of his own accord confront his parents, usually at 11pm as he’s basically had it himself by this stage, and is always frustrated by his mom’s excuses, DD wanted the ice creams, jelly beans, huge afternoon high tea at 4.30pm (so doesn’t get home til 6.30-7pm)…..I don’t have to battle with him as he can see the Jekyll and Hyde turn of our DD when her routine is willfully interrupted by the in laws as they want to be the hero when around my DD, often times at our expense. My husband used to think it was gorgeous that his parents would say as grandparents it is not our job to teach but to enjoy and spoil and now those words have come back to haunt him, as he is left to deal with the fall out of the spoiling. Again, I reiterate, my MIL is not a bad person, but she’s in some sort of crazy competition for my DD’s love which leads her to do things no sane parent would do (she wants my DD to tell her but especially everyone else that she loves maamaa the best……has not happened yet!!!)
Sorry for the long post. The upshot is I don’t think you can change your MIL but you can feel better about it if you really feel your hubby is on your side. I would suggest allowing your hubby to deal with your children when they have their issues if it arises directly due to your MIL’s actions, when it costs him something (his quiet evenings at home, an easy night time bath-story run) then he may spring into action. Good luck and chin up.