I have maybe a slightly different approach, which is very old-fashioned and borrowed from traditional Asian culture. It has worked for me, with a mother in law who objected to me on sight because I was the first serious interloper, the first one likely to take away one of her children and alienate their affections.
I loved my mother. Old-fashioned,strict, pragmatic, hard-working and expecting all of us to work equally hard. She as not perfect, but pretty darn close. A very morally upright person (to a fault; I now understand why and what a burden she lived with). She engendered amazing loyalty in all of us kids, for one another as well as for our parents. But I was the youngest by many years so by the time I was married with my own kids, she was too old and ill to ever come stay with us. I do miss that. She visited our house twice. The last time was one afternoon when she came to see difficult child 3 when he was only a few months old.
mother in law is in no way my mother. It took me years, and my own mother's death, before I could call her "mum". I had to work at it. mother in law is closer in age to me than she would have been to my mother. She's only a few years older than my oldest sister.
But she is still a parent figure and someone deserving of respect, even if at times I have felt she was being silly or unreasonable. Where my mother was unemotional and pragmatic, mother in law is a bundle of emotion and at times childish behaviour. But she is too old to change; it's easier for us to adapt to her, than for her to make any changes now.
When I was a child I read the story of a woman who was tired of her argumentative husband. She went to a wise man and asked him for help to tame her violent husband. The wise man promised to make a potion for her to give him. He gave her a list of ingredients which included the most important ingredient of all - the whisker from a living tiger. At first the woman was in despair, but after a particularly difficult night, she was determined to complete her quest. In the jungle nearby she knew there was a tiger. It did not bother the villagers but they made sure their animals were penned in at night.
So the old woman made a plan - she began to take food to the tiger, left it outside the lair and ran. Over time the tiger got to know the woman and after a lot more time, it actually would come and eat from the bowl as she held it. She was soon able to stroke its ears as it ate, and listen to the deep purring. Then finally plucking up courage, she reached out one morning and plucked a whisker, then dropped the bowl and turned and ran, half-expecting the tiger to strike her down. But she ran unmolested all the way to the wise man's house and said, "Here is the final ingredient - the whisker from a living tiger!"
The wise man said to her, "You don't need any potion. If you can tame a tiger, you can tame a husband."
My best friend who was married to a violent abuser, hates this story, but I don't think the lesson is, "Stay with the abuser, at all cost." I think it says, "If you really try, you can achieve whatever you want, if you really work at it."
The question then becomes - if you need to tame someone like that, you actively choose to do so. You can always choose to go live with the tiger instead!
The other Chinese legend I use to motivate me, is one I actually saw in a diorama while we were on our honeymoon. I've always respected the way Chinese people treat the elders in their family. But this one was extreme - it was the Chinese equivalent of the Saint of Filial Duty. As depicted in the Tiger Balm Gardens in Singapore, Madam Tang kept her toothless mother-in-law alive by breastfeeding her. The diorama depicts the woman's baby crying in the corner while the mother in law is fed first. Madam Tang is held up as a shining example of filial duty. While I don't ever want it to get that far, I see my own duty to husband, to involve caring for his mother (who is the woman who gave birth to him) as best as I can. I don't have to feel for her what I felt for my own mother - that is not possible - but in my own way I have put in effort to befriend her and do my filial duty with absolutely no indication of resentment. I know she used to resent me a great deal, initially she did her best to block our relationship. But I don't think it was personal. Even if it was, the best revenge is success. I've always found that the best ay to deal with jealousy is to make friends unexpectedly. She is now part of the package deal of husband and as such, to be embraced.
Here is a link to Madam Tang.
http://history.cultural-china.com/en/38History5741.html
I have to go to mother in law's now to finish working on dinner with her. I need to involve her so she feels useful. I'll take my knitting so I have something to work on while dinner is in the oven, so she doesn't feel I'm rushing off home for a while.
We do what we can while we can. I can't do this for my mother, so this is the next best thing.
Marg