<human>: Can you succinctly summarize the text in 1-3 sentences?

My brother and I had a rough upbringing. He was kind of the golden child and I was the black sheep. My parents were verbally and physically abusive towards me and I eventually ended up in foster care after my parents agreed to voluntarily go through with that. Before I left, my parents always kind of recruited him to "help" them during arguments, something he was all too happy to do. But afterwards, I think they shifted their issues with me to him, but he let it happen because they paid for him to go through college and grad school, and gave him free room and board through all that.

That was about ten years ago (except for the last part). Fast forward to today and we've mostly moved on after lots of therapy and time. The problem is that my brother still feels really bad about what an asshole he was back then and is still kind of trying to "atone" for it…which is a problem because A. he's not that snotty teenager anymore and B. he's acting like some kind of immature child when it comes to dealing with conflict.

Most of the stuff he posts on Facebook consists of "zen" and eastern medicine-y kind of content, and to each their own, but he's very self-righteous and a little bit arrogant about all that at times. He's also pretty thin-skinned and tends to avoid conflict and refuses to respond when asked about some of his actions; even little things like when our mom asked him why he hid some of his Facebook content from him (some photos and stuff from school our aunt mentioned to her, not sure on the details there).

I'm just so frustrated about how he's been acting and I don't know how to handle this situation. I know I'm kind of all over the place with this post, I'll be happy to clarify anything. Thanks in advance for your help! :)
<bot>: My brother is passive-aggressive, immature, and full of himself, and I don't know how to handle this anymore or how to communicate with him.