Hi Pandora - and welcome !
Well, it sounds from a distance like the 3 of you are not "really" that tight.
If you were I suspect things would have been discussed somewhat more openly.
Is the way this has gone down the right - or best way ? Definitely not !
But I suggest keeping it somewhat in perspective and remember we're all still human and figuring out a lot of things as we go. It really is (from what you write) nothing personal towards you.
When anyone is in a crisis - whether it's between 2 people, a family member, a job, you name it - it's easy to get hyper-focused on the problem and shut out most everyone and everything else.
In an ideal world (maybe), they might have have brought you into the fold, shared the problem with you, let you help if you could or at least be there as support. But it's also possible they tried to shield you from whatever it is - didn't think it fair to load you down with it.
No way of us to know.
But it's another one of those golden opportunities to really get to know each other on a deeper level. Because crisis WILL come again - someday - sometime. You guys all have to make up your own guidelines on how you handle it best.
Don't take it personally. Just express your hurt and disappointment and let them know (IF it's true) that you don't need to be sheltered and would prefer to help if possible.
My thoughts anyway...........