Left out of brothers party

Hi, hoping for some advise.
My second eldest brother recently got married. I thought we were pretty close, I certainly saw him as a potential best man in my wedding. Whilst my oldest brother is not that close with him and really annoys him. Whilst my younger sister is closest to him.
He chose to have 4 groomsman (one lives overseas) and he left me and my oldest brother out. My little sister was offered to do a reading and told she was emergency for the bridal party by my SIL. The grooms from overseas couldn’t make the wedding so they chose to have 3 in bridal party instead. I have felt sick about this since finding out. My mum was the one that came to me and told me that I had been left out. She said she was disappointed that family members were not included which then got me thinking and browsing Instagram. From there I saw that All the guys who got married had their brothers in the grooms party. Including the ones that has been chosen to be grooms, they had 5-6 groomsman to fit their brothers in. Perhaps this is a sign of how we’re not that close. Perhaps the oldest brother cost me being in there because he didn’t want to have him in, and also didn’t want to leave him out by choosing me. I texted my brother how disappointed I was and he said “i hope you understand” without any explanation. I have felt a sense of distance from him ever since. I think the bride doesn’t really like me even though we started on good terms, and I have been nothing but kind to her. My oldest brother doesn’t get on that well with her either. The fact they gave my sister a role hurt. I also had uncles asking why I wasn’t speaking on the day which dug deeper and I had to lie and pretend it’s a good thing I didn’t have to speak when really I would have loved to. It’s his biggest day and I thought we were close…I find this very hard to bring up now that the wedding is over but the reality is I don’t think i will have him in my party now. At least whilst it’s raw I feel he went about this the wrong way and didn’t value our relationship to explain it to me when I told him my feelings about it. He just wanted to avoid the conversation which makes me feel there’s something he’s not telling me. Whatever the reasons; I still feel sick about it because everyone else includes their siblings 90% of the time. It’s rare that they don’t. Any advise on how to deal with this now would help.