Friend problems

(WARNING: BAD GRAMMAR🫶) So this all happened in like a week or so, and I need opinions from others on what I should do next. I am in this friend group where it feels like it has an obvious ranking system, there is this one friend who I'll call Z, Z would ghost us from time to time but it was more noticeable when they had new friends, and they would boast about how great their new friends are and how I am 'Just like them, but they're a better version than you' it obviously hurt to be compared like that but I let it be, because apparently they're 'going to kms because of friend problems' so their situation is more serious(they've been causing most of the friend issues) but our group of friends then made a group chat in hopes to find ways to help Z out of their mental space. It has gotten to a point where no one can vent freely because Z seemed to be the main topic of everything because Z's closer friends would push the convo to be about Z. Z started even testing us, having their closer friends make us confront Z personally because it was our fault for Z to ghost us?? But Z themselves said they would hide from us and expect us to wait for them outside of their classroom. One of my friends said they tried to talk to Z, but Z hid behind their new friends and practically ignored them. I thought Z made their close friends to make us confront them, what was the point of that whole test other than proving that Z wanted to feel important and make their friends worry constantly until their own mental health is being brushed off as 'unimportant' Should I ghost Z and never speak to them again so I can finally be able to freely vent without feeling pressured that Z has it worse, or continue to help them until I feel mentally drained. Please help