TITLED IT WRONG! AITAH FOR BEING HURT BY THE WAY MY SISTER TOLD ME ABOUT HER CHOICE FOR MoH? (Edited on advice)

Me (39f) and my sister (36f) have always had a rocky relationship but I thought we had got past that stage and were doing better. Even when we weren't getting along, we 99% of the time managed to remain civil when the family got together.

I have had issues with anger since childhood. Looking back at that and other things from childhood, my docs think I need an ADHD referral but it's 7yr waiting list. The history of anger is the pertinent issue though.

At my son's birthday party recently, my sister asked me and my daughter to be bridesmaids. At first I was delighted, didn't give it any more thought, just enjoyed the moment with my daughter. A few minutes later though, she casually threw out in conversation that our SIL (bro's fiancée, will be wife by then) is MoH.

This felt like a slap in the face so I calmly grabbed my coat and took myself off outside and spent the rest of the party alone. When the realisation set in that every adult in the house bar my husband and I knew beforehand it was like a punch to the gut.

If it had been a childhood best friend or someone she'd known for 20 years it would have been different. Also, I know SIL was surprised to be asked and I hold no grudge against her although I was slightly resentful for a day or two.

While I was initially hurt by her choice for MoH, I do fully understand and accept that it is her choice and I wouldn't want her to change it. What hurt the most when I thought about it more is the way it was done and the casual manner it was thrown out there.

Ten or fifteen years ago, I likely would have stormed off in an absolute rage and told the lot of them to go fork themselves. I don't do that now. I have spent time and effort to not be like that anymore.

It took me a few days to be able to form a coherent thought that didn't result in me breaking down feeling like a worthless mess. When I could, I finally spoke to my mum. She told me that she did know about MoH but not about when sis was going to tell me.

After a few more days and talks with mum, explaining how I felt and why I was so hurt, I told I was ready to hear sister's side when she was ready to reach out.

This was mid march.

Fast forward to the last few days.

Sis texted me Friday, on the offensive. Calling me out for "throwing a fit" (actual quote, not AI) and telling me that my reaction has hurt her. She did apologise for the timing but even after I explained that while the choice for MoH was the inciting incident, by the end of the conversation she still had it in her head that that was the main issue because I "didn't get what I wanted" (that one will come back later).

Sunday, I get ambushed by our brother (33m). Full on purposely didn't give me a heads up he was coming so I couldn't say no. Not that I would have because despite what my family seem to think of me, I do want to get past this with her. We went to get a coffee and he spent a little time hearing me out and then the better part of an hour basically demanding that I apologise to my sister. Even if I don't mean it, which I abhor. We left it with me saying I'll think of something to say to try to start the ball rolling.

I spoke to my mum on Monday to talk to her about it. I asked her to try to articulate to me what it was I did wrong and being expected to apologise for. She couldn't. She said I should just acknowledge that my reaction hurt my sister. That feels like being asked to apologise to my sister because she "didn't get what she wanted" from my reaction.

So I spent what time I could yesterday (she's not the only thing going on in my life) trying to figure out what to say without it coming across as some fake ass BS apology, think "I'm sorry you feel that way" or "I'm sorry that....but...."

Then I get another message this morning expressing disappointment that I haven't apologised and informing me I'm no longer part of the wedding.

So unbiased, no skin in the game opinions are needed for my head.