I'll share my story, and maybe this will help someone out.
Growing up I had an older sister and younger brother. We always knew our dad was a bit off. Cold, distant, didn't interact with us unless it was for disciplinary issues. He never abused us, but he was on the neglectful side.
When I was 16 he had a seizure (lifelong condition) and my mom tried to get him to go to the doctor. He pulled a knife on her and threatened to kill her. Police were called, engaged him in a car chase, eventually pulled him over, arrested him, and he spent a bit of time in a rehabilitation home.
This happened a couple more times, the last time included him actually pushing and trying to hit my mother in a Wal-Mart parking lot. Yet after the blowback from the first incident my mother doesn't want to report his actions to the police whenever something happens.
It's been pretty quiet; last incident was around 5 years ago. But the effect it had on my siblings has been the real consequence.
My sister has terrible mental health issues now. She's on 4 medications for mental health and has been diagnosed with bipolar disorder. Mix that with excessive alcohol consumption, and you can see how trouble has arisen. At one point last year she was taking her meds, drinking, and smoking marijuana and had a mental breakdown of sorts.
My younger brother also took it pretty hard. He dropped out of high school but managed to get his ged online. Except for a failed one month period where he moved out, he's been living at home his entire life (now 21). No college or educational aspirations. He's bounced from crappy job to crappy job. He's developed a heavy marijuana habit and can't attend any family function without blazing up first. He's currently on anti depression meds and has cut off all contact with our family. He's basically a stranger living rent free with my parents.
I can't really tell how it's affected me. I know I have trouble establishing real relationships with people, and I tend to keep any personal info to myself. I guess I have a lot of shallow friendships, and even my best friend doesn't know about my family life. I don't know if that's due to the past, or if I just turned out that way. Thankfully I haven't developed any mental health issues from my family drama, and I really believe that running and living a healthy lifestyle have helped contribute to that.
My advice is to find a way to forgive your parents/siblings for what they've done or continue to do. Any anger or resentment you feel is only going to hurt you, not help you. Seek professional help if need be. Eliminate your pride and reach out for help. People want to help you, but you have to want to be helped for real life change to occur.