Oh, I’ve got a SIL like this.
What’s happening here, is that she feels her status and place in the family is threatened by you. I’m not joking, I’ve had it happen to me. My SiL’s take on it was that I am not family, I am an interloper, and my place is at the bottom of the ladder and hers is on the 2nd to top rung under their mum and dad. My DC are part of HER family, and are her blood, but I am just a walking womb and not family. My SiL was single till 50 and has no DC. Mine are the only DGC.
We have had many battles in the past, and she didn’t win all of them. When I decided that I was no longer prepared to be a 3rd class citizen when with them, I went LC with her. She doesn’t live with PIL so it’s a bit easier. She succeeded in pushing me out when I was younger, in the sense that she stopped MIL getting to know me, and wasn’t allowed to spend time with me. I’ll never forgive her for that.
I organise most things and I don’t include her. I invite PIL but not her and her BF. When she invites us, I am always busy. I’ve not seen her for 18 months. She recently told my DH that she wants to get to know me better. What after 30 years? Do you think I’m that naive that you are only doing it because you are excluded from the good stuff like my kids milestones, their parties, Christmas and days out. We went to Lapland a few years ago and she went ballistic because we didn’t invite her or PiL. I mean, the entitlement.
Your MIL has done the maths. DD is her child, she lives with her, now she has to put up with her upset, she’s going to probably have to look after MIL in her old age. Your MIL is sticking with her insurance policy and gaslighting you.
You need to get over your upset somehow. If you are damned if you do, damned if you don’t….waste no more time on them. Tell your DH he is to deal with HIS family from now on as they treat you with disrespect. Back out slowly. Drop the rope.
My greatest revenge is to live well. I’m really happy to see PIL when I see them. But I’m super dooper busy. We’ve been doing this, and doing that, life is so busy and great and I don’t have a second to waste thinking about your insecure DD, my SIL.