AITA for refusing to give my late mother’s wedding ring to my stepsister for her wedding?

I (28F) need an outside read on this because my whole family has decided I’m the villain, and I’m starting to wonder if grief has just made me blind to how I’m coming across.

Some background. My mom, Diane, died of ovarian cancer when I was 19. She was sick for two years, and near the end, she gave me her wedding ring — not as an heirloom to be passed down someday, but directly, with instructions. She took it off her own finger in a hospital bed and put it in my hand. She told me it was mine, that she didn’t want me to inherit it after a will reading with lawyers in the room — she wanted to give it to me herself, while she could still watch me put it on. I wear it on a chain, not my finger, because it’s a size six and I’m not, but it hasn’t left my body since the day she died.

My dad remarried four years later, to a woman named Carol, who has a daughter, Brooke, from her first marriage. Brooke is two years younger than me. We were never close, but we were never enemies either — polite at holidays, occasional texts, that kind of relationship.

Brooke got engaged in the spring and is getting married in six weeks. About a month ago, Carol called me — not Brooke, Carol — and asked, in this very casual, already-decided tone, if Brooke could “borrow” my mom’s ring for the wedding, as her “something borrowed.” She said Brooke’s biological father has never been in the picture, so she doesn’t have any of his family’s jewelry, and Carol thought it would be “so meaningful” for her to wear something that had been “in the family.” She also mentioned, almost as an aside, that Carol herself never had a nice wedding ring the first time around, “so there isn’t really anything else to give her.”

I said no. Not cruelly, I don’t think — I explained the ring isn’t a family heirloom in the “we all take turns” sense, it’s the specific object my mother put into my hand while she was dying, and it doesn’t come off my body for weddings, borrowing, or anything else. Carol got quiet, said she understood, and hung up.

Then my dad called. He didn’t ask, he told me: he said it would mean a lot to him if I could “find it in my heart” to let Brooke wear it just for one day, that it would “heal some old wounds” in the family, that Carol has done so much for us and this was a small thing to ask in return. When I pushed back, he said something that’s been sitting in my stomach like a stone ever since — that my mom would have wanted me to be generous, that she “wasn’t a small person like that.”

I told him he doesn’t get to tell me what my dead mother would want regarding the one physical object she put in my hands herself, and I hung up on him too.

Since then it’s been a slow-motion pile-on. My aunt (Dad’s sister, normally someone I’m close to) texted that it’s “just a ring” and I’m “punishing a 26-year-old for who her mother is.” Brooke herself finally texted me directly, and to be fair to her, it wasn’t demanding — she said she felt weird even asking, that her mom had pushed her into it, and that she didn’t want to be the reason for a family fight. I believe her. I don’t think she’s the villain here. But “she was pressured into asking” doesn’t change what I was pressured to give.

The wedding is in six weeks. My dad says if I don’t come around, it’s going to “cast a shadow over the whole day” — which I’ve now been told, more than once, would be my fault.

Update, a few days later: My dad showed up at my apartment unannounced, which he never does. He didn’t yell. He sat at my kitchen table and cried, and said he still misses her every day too, and that he thought sharing the ring might be a way of keeping her present at an event she’s never going to see. That got to me more than any of the guilt-tripping did, and for about an hour I almost caved. Then I remembered that “keeping her present” was never Carol’s or Brooke’s to define — it was my mother’s, and she already defined it, in a hospital bed, with her own hands. I told my dad I love him, I’m sorry he’s still grieving too, and the answer is still no. He left without saying much.