Loss of friendships

I spose this is more of an outlet than a question but any advice is always welcomed!

My friendship group of about 15-20 years, doesn’t feel like a friendship anymore.
I appreciate and respect each and every one of them so much and I thank them for their years of friendship but when I stand back and take the rose tinted glasses off I see it for what it is, maybe friendship out of responsibility because we have all been friends for so long??
I message them individually and don’t get replies but they will message the group chat and each other individually. I ask to catch up and no one responds, a few of them catch up on their own too.
These last 3-4 years I don’t think any have actually reached out to me. Don’t attend events I host etc
They are going through so much, loss of parents, divorce, sick family members, miscarriages, massive family issues and I try and be supportive and check in but after not responding I no longer reach out. They will lean on each other for support and I’m so happy they do have each other but it just hurts I can’t be that person for them.

I do have other friends, some that have been around for 10+ years, some less but we always seem to catch up, they make time for me and I love and adore them too!
I’m just so sad that my oldest friend group isn’t the same and I spose I need to mourn that loss :(
I have brought up my feelings with them before and I know they are excluding me maliciously but if it’s not organic I’m not going to fight for it anymore :(

Sometimes a friendship breakdown hurts worse than a failed relationship and I spose that’s what I’m going through atm. I’m not angry and would always hold space for them if they need me but I also need to look out for my well-being and guard my heart now, this rejection sucks.