Three years of being excluded by my former BFF/cousin

TLDR: Should I cut my losses and move on from my longest time friend group thanks to my former BFF/cousin who dumped me 3 years ago? We are both 41F and moms with kids the same age.

My cousin B and I (S) grew up next door to each other in a midsize town and shared a lot of the same friends since high school. This high school friend group has remained close throughout the past 25 years. We would get together several times a year for big group weekends camping or getting a cabin, holiday parties, birthdays, even trips to Mexico. These were some of the most fun and memorable experiences for me and my kids. 

Three years ago, I split up with my then-husband (C). My ex and I were very close to my cousin and her husband, as I mentioned, we both had two kids the same age and the kids were close too. The early part of the split wasn't easy, but today my ex and I are great friends. He is in a relationship and I am single but happy for him. C is cordial with B and her husband but they aren't super close now that we're not married anymore.

However, B made some moral judgments about elements of the split early on and completely cut me out of her life. Blocked me on her phone and every social platform. She's the alpha of the friend group, so while my other friends made attempts to invite me to group things initially, B would say "If S goes I will refuse to go" and so I was just excluded. This has become the new normal. I've maintained solid friendships and one very close friendship with all the other friends but they haven’t gone out of their way to try to include me in the group stuff.

B has also done the same type of exclusion with our large family and group of cousins who grew up close in age and close to each other. B hosted a bridal shower for another cousin's fiancee at her house and invited every female family member except me. She also pulls the same "if S is there I won't come" type of thing whenever she can. She was very cold to me at two family weddings this summer.

These last three years haven/t been especially great for me - going through a divorce and other things - and because of B, I've been excluded from some of my most important sources of support, my friend group and any type of family thing she can control. I'm not sure if she's being intentionally cruel or simply indifferent.

Some people have confronted her about it directly: my ex, my mom and B's sister who all have my back and can't believe B is behaving this way. As for my other friends, they seem to have accepted the new group dynamic while still being friends with me on the side.

She is my COUSIN. we go back literally forever and I'm part of the family whether she likes it or not.

Will she ever change?
Is it worth continuing my 1:1 friendships with people who are fine with B setting the new rules?

WWYD.