What's the problem with my dad?

My relationship with my dad is at most abrasive. My dad is a British graduate and used to be very bright. He was offered to pursue his masters and doctorate in UK but he declined. He worked there for 8 years before returning back. His family used to dictate his every move till his mother passed away. In UK he was very carefree and happy, but here he's bitter and cynical. My parents married by compulsion. They hate each other. When I was born he wasn't there to greet me and my mom, and his excuse was he's working. My dad controls my mom even when she used to work. My mom had to sacrifice everything( including her health for me) despite his abuses. MY dad has changed many jobs ever since. He was abusive to me and my brother till my sister was born. My dad says he's sorry but he doesn't seem to be genuine. My parents argue almost everyday (it was intense when I was young) and my mom has attempted suicide many times. My mom wanted to divorce my dad but she can't because of me and my siblings. Only a few months ago he apparently seems nice to us. To the outside world, he's damn charming and portrays himself as a saint. When I was young he used to be drunkard and he has many traffic violations(thousands of dollars). And he is gullible to other people's say. He is easily swayed by others opinion and never listens to my mom/my opinions. I was raised for a year by my late grandpa. Then, without any choice by ultra-abusive nannies(they physically abused me). I just can't forgive my dad because whenever he says he's changed, he reverts back to square one. The only thing I know is that he is narcissistic. He uses my family to exalt his image. He never plans anything, including financially, and he is impulsive. He used to have anger issues too-reason why he was physically abusive. He never shows any remorse or guilt. He doesn't hit my mom but when accidentally injure her he just leaves without a sorry. My brother is leaving soon to US on scholarship-his only emancipation from this rut. He is lucky he's top a student/valedictorian of his high school. I've got 4 more years till I can get out(in uni now).