He blocked me everywhere 1,5 months after breakup & no contact

I don't get it. It's been a few weeks since this happened and 2 months since the breakup, so the initial pain has blown over and this is not a panicked post about how bad this hurts and how all my hopes of getting back together are now shattered. I just don't understand what the sense behind this is and I'd like to hear some opinions, because this was a messy breakup/relationship and I don't want to be blindsided by another blow against my peace again.

Background story:
After our initial breakup, I withdrew from all shared social circles and social media, because our breakup was caused by our problematic mutuals and their bs.
It was a good call, because things there MASSIVELY went out of hand with the main problematic person deleting lots of stuff, first selectively (again - to change the meaning of conversations she and I had in DMs and make me look bad with the context gone - 99% of those conversations were intentionally fabricated by her like this and she was doing this for months) and then all messages she had ever sent me. Doesn't matter. In worst case I have enough proof to fight back, but I hope I won't have to.

Well, what happened is, he and I broke up two months ago.
I laid low, took my time to grieve, to calm down after all this nonsense had been going on for a year.
Anxiety went down, thoughts and feelings started to clear up etc. Basically I freed myself from the influence of the situation, didn't bother to message back any of the mutuals reaching out, because I simply needed this time for myself and didn't want to answer and have new problems coming my way. I just wanted to calm down, find clarity and heal.

After 1,5 months, on Halloween, I returned to my social media and made a Halloween post, tagging my friends, who were involved.
In response, he blocked me everywhere, removed each other from all shared posts, gifts, anything we ever worked on together or gave each other online. Made a post about cleaning up. Yes, I went and checked, because I was a bit shocked by such an intense reaction after such a relatively long no-contact and calm down period.

He posted on his other pages that he doesn't want contact with anyone anymore, except his best buddies.
And after all this bs, same. He got hurt, I got hurt. People were shit and I am so sick of how humans can be at this point
I'm not gonna get into all that happened, but it was ugly. Jealous friend in her midlife-crisis unhappy with her marriage destroys local couple's relationship.
Add some other, smaller factors, both from other people and between him and I and you have our story.

My question is:
Why does a man do this, almost 2 months after the breakup?

Is he still hurting so much? (I hope not. I won't lie, I still care and I just hope he's not a complete mental health wreck after this and suffering, because I don't want that for him.)

There's a possibility our mutual (who he still hangs out with) has used the time after our breakup to persuade him even more of how evil I am. Probably that's the reason why she deleted all messages in the fashion she did. So there is that. But still... he could have blocked me all along.

Why do that in response to a simple Halloween post? Did he think I'd just abandon all my social media and never resurface again online? He also left some bigger groups in which I had been barely active in but he had been, also in response to that.

Somebody explain to me the psychology of this reaction, because while I'm overall doing better after the breakup, than during the relationship, I've been rolling this over in my head for 2 weeks now and it just won't leave me alone, no matter how much I distract myself or let myself feel the feelings or journal.

I need somebody else's thoughts, to get a bit of closure and stop pondering. You'd do me a great service. 🙏