If you saw a bridesmaid crying ugly tears (not necessarily happy) what would you think?

This. Absolutely this.

I genuinely don’t understand what your sister won’t be able to do married that she could do single, apart from pull men. Which is surely not a ‘together’ activity anyway? I’ve been married for 20+ years and still go on holiday with friends, spa days etc.
Please hold it together on her wedding day.

I was a carer for my terminally ill parent throughout my teenage years and into my twenties. It’s never occurred of me to think of it as a ‘sacrifice’ or that my life was on hold - that just is life, for many many people. I don’t feel robbed of ‘carefree’ years. Twenty years later I can see in reality it was such a short period - 11 years out of a lifetime - where I prioritised my parent whom I loved very much.

I think you need help working through this because feeling so robbed and thwarted by it is going to make your future darker than it needs to be.

People will assume they are happy tears. My DH and I blubbed (silently) all the way through my DSD's wedding ceremony because it was so beautiful. We are very sentimental. Luckily formal photos had already been done so it didn't matter what it did to my make-up.

Of course if you cry and are asked about it you say "because it was so beautiful" not "I'm sad for what we are missing out on".

I'd assume there had been a bereavement or similar that the wedding was bringing up. Big life events can be emotional occasions.

OP, gently, why do you imagine other people’s twenties are all Disney and carefree? I had cancer myself in my 20s (recovered well), a friend of mine was orphaned by the time he was 20, another good friend was hospitalised with anorexia, more than one lost a parent in their 20s — plus I think a lot of people have quietly, ordinarily ‘not fun’ twenties as they figure out how to be adults. I don’t think it’s helpful to think of your mother’s illness as having robbed you of some carefree period everyone else got.

You keep talking about being ‘carefree and single’, but what do you think you would have done on a night out or weekend away with your sister before she got married compared to after?

I sum still with you?

This

I wasn't gaslighting you in the slightest.
It was a genuine question!
🤦🏼‍♀️

I think you're overthinking how much this will change things. There's very few things single sisters can do that married ones can't.
I've never gone out on the pull with my sister so it made no difference to our dynamic when we each got married.

Weddings, births, deaths are all big moments of transition and bring things to the surface which day to day we have under control.

When I lost DH very suddenly and too early I kept it together pretty well through the immediate aftermath, the long wait until we could hold a funeral and then through the funeral itself. Day to day I’m very stoic in public at least and keep on carrying on plus I had young adult children to consider.

Then one of the DC married and when DH was mentioned as part of the ceremony I was overwhelmed by the reality that he would miss three of their weddings and DGC and that the retirement we had planned together would never happen. Loads of things not relevant to the wedding itself are brought to the surface by these big moments.

Luckily my other DC and friends, family just past me the tissues to mop up any tears leaking out during the ceremony and squeezed my hand rather than wag fingers and tell me to get myself under control and stop making it all about myself.

I hope you have someone to pass you a tissue and squeeze your hand on the day. Talk about it to your sister before hand - she may be feeling much the same.

You're saying us and we but really it's me and I. She obviously doesn't share your longing to be free and single. It's understandable that there is sadness and regret about your younger years but your emotions about this wedding are misdirected. It's not the time or the place. You're making her wedding about you.

I don't understand why you're getting such a hard time OP. Whilst you are happy for your sister, it does mark the end of any era, of singledom and all your plans. You've both sacrificed so much for your DM and both deserve happiness. Your turn will come, if that's what you desire.
I'd sit down with your sister and have a heart to heart, tell her about your regrets, fears and cry, a lot.
Before my DM's funeral I listened to the music she chose over and over again until it didn't trigger heart wrenching tears. Sure I still cried but it wasn't overwhelming.
Not sure that helps you OP but I get you.

I am a crier and I just wish it was as easy to control the tears as many mntters here have commented. I have been like this since a young child and would have “ curbed” the habit if it was possible because of the shaming, teasing etc. So please do not be so judgmental. I do not seek attention and the OP states that nor does she.

Can't imagine that'd be a fun holiday for her sister though!

I get it @Friko , honestly your only mistake was reading page 1 of an aibu thread, it's full of people who click every thread as soon as it's posted and put a knee jerk judgey/emotionally stunted response!
My recommendation would be to discuss with your sister before hand and say as it's her day, ask what she would like you to do if you're feeling overwhelmed. Then you can have an exit strategy in case you need 5 minutes.
Your emotions are your emotions, they can't be switched off and they are important, even if not always convenient. Take care and I hope your next chapter goes better than the current one.

Wow the level of compassion is next level here…..

These are some of the most remarkably hostile responses I think I have ever read on MN; it's like people didn't bother to read the first post properly.

The OP and her sister have been carers for a seriously ill parent since childhood - that's something that most of us are lucky enough never to experience, and it is a profoundly different experince of youth than most children and adolescents get to have. Of course a major milestone for her sister is going to bring up lots of big feelings for the OP; it's a traditional marker of the end of a particular stage of life, even if in practice the differences between being unmarried and married are much less now than they were a few generations ago.

People cry at weddings all the time, OP; as long as you're not wailing aloud I don't think anyone will bat an eyelid. I hope it's a lovely day for you all.

Don’t spend time crying. Tell yourself this is one of the most special days in your sisters life, if not the happiest. Celebrate this day with her, for her. Whilst you are in tears you will miss those rare special moments that you will be able to recapture and reminisce with your sister in the future.

What an odd assumption. Most grooms are just generic men so not that coveted, OP didn’t mention her sister was marrying Tom Hardy.

Of course people have been 'incredibly upset' and cried. But this is OP's sister's WEDDING - a happy occasion.

No need for distress.

I’m sorry you’re getting a hard time op. I’d never think the sister of the bride was attention seeking if she was crying at the weekend. Especially if they’d had a rough time with their mothers illness.

Also op, my sister and I are married and we regularly meet up and go away for weekends. Sometimes by ourselves and sometimes with our dc.

I'm sorry but I think she'd be making the day about her.

I understand how difficult you've had it but I'd really try and find a way to deal with it which doesn't involve crying ugly tears at your sisters wedding.

I think part of the problem is that you’re referring to ugly tears and ugly crying, which is fairly specific. Ugly crying is sobbing, gasping, red-faced, snot-nosed, etc. You absolutely cannot do that at your sister’s wedding during the nuptials. It would be completely inappropriate; no one would hear a word as they’d all be staring at you.

I also had my twenties and all those experiences taken from me so I have a lot of empathy and understanding there. But if you’re genuinely talking about making a spectacle of yourself as she’s trying to marry her future husband then you need to excuse yourself rather than ruin her day.

If you just want to mourn the experiences that you didn’t get to have and aren’t at risk of bombing her ceremony then mourn away. I’m afraid you’ll still get responses based on your OP though.