Goodness...who died and made her fashion and culture Goddess? Is she Lady Catherine De Bourgh?? My BIL's ex-wife was....not really like THAT so much, but very controlling and everyone walked on eggshells around her. We couldn't do anything without her permission. Like, if we were planning Christmas dinner, we had to check with her before anything was decided, and she'd throw a fit if things weren't done her way. When I first moved over here, it was in November, about a month before my birthday. My mom and my dog had just died, I had given up my job, my home, EVERYTHING to move overseas where I knew NO ONE, and didn't speak the language. She didn't feel comfortable speaking English, so she basically wouldn't talk to me. My in-laws insisted I HAD to celebrate my birthday, even though I didn't want to. They basically did the "You're living in OUR house, so you have to live by OUR rules, and we want you to have a birthday party." They not only invited BIL and SIL, they let them pick the date so they would know it worked for their schedules. So we said we'd do cake and such at 3 on that day, and then have a nice dinner together at 5 or so. No problem. They showed up at 4, wouldn't eat the cake, and then left 45 minutes later, before dinner, because "We've been planning to go to the movies with Stef for months, so we can't stay." THEY picked the date weeks before....if they had plans, why did they pick that date? And how do you plan the movies MONTHS in advance when you don't even know what exactly will be playing when??
Then at Christmas, she insisted it was just too expensive now that my husband had brought me over, so instead of buying presents for everyone, we should draw names, and everyone just buy one gift, for a maximum of 12.50 euros. Everyone should make a list of things under that amount so the person who got your name knew what to get you. DH got her name, but she was too lazy to actually go and look for things that were under that amount, so almost her entire list was over the price limit that SHE set. The only things we could get from her list were a lipstick, and kleenex. (Yes. She put kleenex on her Christmas list.) Not very much fun to give really, so we decided to be creative. We got a big package of the little pocket-size kleenex and I wrapped them in different ways. Two packets stacked on top of each other, two end to end, 4 in a rectangle, etc. That way she got kleenex but had more to unwrap. I grew up poor....all my gifts were things I needed, like new socks, batteries, scotch tape, shampoo. It was just so we had something to open, and we appreciated that we got a gift. Well, she obviously had never been poor, because the first packet she opened she frowned and said "This wasn't on my list." We said yes, it was....and we showed her the list. "No, I wanted the kind in the box. Not this." But she hadn't specified. Then every time it was her turn to open, she would just go "Oh....it's going to be more of these. You go." and wouldn't even open them. My MIL had even bought a few things for her, like a glass cake plate. (She got me one, too) SIL says "What will I do with this?" So then the next year, we had to do things differently, because she didn't like the way it turned out and she hadn't gotten anything she asked for except lipstick. And every holiday, birthday, etc was like that. Oh no, you couldn't have your party that day because her aunt was celebrating this, or we couldn't do it that way, because she didn't think that sounded fun.
She even kept my BIL from coming to our wedding. She hadn't wanted to come in the first place because she didn't want to go to the States. My in-laws were paying for them to come. My MIL had wanted to fly in a week or two early and visit New York and stuff before coming to the wedding and SIL didn't want to. So they canceled. Then September 11th happened a week and a half before our wedding and she refused to get on a plane, and told BIL that he couldn't come either because it would make her too nervous that he was on a plane. So he missed our wedding. He was supposed to be the best man and he called in tears saying she wouldn't let him come, that if he came, she said she would have to go to a mental hospital. That really manipulative, controlling thing is just....

I feel your pain. Is there any way to just...avoid her? Spend as little time with her as possible?