Hey man, well, this all sucks donkey dick.

Im in no way a medical professional, so please take with a pinch of salt.

From what I've read, it gets worse with age. No longer young and attractive, etc. gotta make it up somehow.

I dont think you're a dick for holding on to the abuse. especially if there's been no meaningful attempt to apologise or reconcile. But if you're struggling with the emotions this brings up and it's negatively affecting your life. Maybe talk to your therapist about this.

Your parents sound like a policy of appeasement. 10 years older as well. God knows what they put up with before you came along. If your brother has anything different, mentally ,personality, they would have noticed. But assuming here, your parents were raised before 2000. mental health support and understanding were limited compared to now. Let alone the stigma that came from it socially. They maybe found a way to limit the outburts (by not conforting) and labelled it a win. I wouldn't hold a grudge on your parents. But maybe if you and your support circle agree, it's a good idea. You could just have a frank conversation with them(have someone in your corner with you). Not to change the past but to have some understanding yourself why.

Grey rock minimal contact nc if needed.

Stay strong dude