Messy breakup in a friend group

I got out of a relationship about 2.5 months ago. I hesitate to even call it a breakup because it was very one-sided and felt completely out of nowhere.

My ex is a coworker and part of my core friend group. We dated for almost four months, and up until the end, the relationship genuinely felt great. Then, seemingly out of nowhere, they became cold and distant. Two weeks later, I asked directly if they wanted to keep dating, and they said no. That was the end of it.

A couple of days later, I reached out hoping for some closure, but I did not really receive any. Since then, they have been treating me like I do not exist. They do not acknowledge me in group settings or respond if I speak. At this point, it feels mean and unnecessary. A few friends in the group have even described their behavior as petty.

The hard part is that while some friends privately agree it is uncomfortable, no one seems willing to address the tension directly. I do not want to lose my friend group, but I also do not know how to keep existing in this dynamic. Ideally, I would like to find a way to coexist peacefully with my ex.

I am struggling because I am afraid of losing my friends, and I am also afraid of losing my ex entirely. I understand people may have opinions on that, but I am asking that this thread focus on how to navigate the social dynamic and coexistence piece. I am willing to be patient and do the work on my end.

What can I realistically do at this point?

If more details would help, feel free to DM. I am trying not to overshare here.