Need to vent about my sister.

My sister is getting married to the love of her life. Her and I are 2 years apart and she’s my only biological sibling we had each other growing up. As we got older we were completely different I was wild and she was calm. Anyways I got married 6 years ago and of course asked her to be my maid of honor knowing she’s my sister and will always have my back. Well when she got engaged we were not speaking because her and my mom were talking about me and I had found out and was upset. We eventually made up and things have been great for the last year. Her bridal party has been chosen she has 9 bridesmaids 1 including our younger sister. I’ve kept my mouth shut because I know that it’s her day and choice, she’s having my 2 kids in her wedding. But I’m devastated. Her bestfriend and her were arguing when she got engaged and didn’t make up for months afterwards and she asked her to be her matron of honor. My mom told her I was upset (I should have known not to voice my feelings) and now out of pity I’m wearing a bridesmaids dress and walking down the aisle with my kids. I’m not a bridesmaid but will be wearing the dress. My boyfriend and friends don’t think I should do it because I will look like an idiot sitting down after walking the kids. But I plan to do it because she asked me. I’m torn I don’t want to cause drama it’s not my day. I have a lot of mixed feelings! Mainly I’m hurt. Thanks for listening.