Abusive father hurting girlfriend?

[Derrick]

Alright, it's a long, long story. I'll try to keep it as short as I can. I used to ask this on Yahoo Answers, gave up and searched the internet for a better site, came across this thought I would give it a shot. Here goes... I am 16 years old (male), my father was abusive for 20 years, emotionally and physically, he attempted to strangle my oldest brother while I was in the room, among other things. He was arrested multiple times, not for long periods of time we lived in a secluded area where the police weren't very good with domestic abuse. I have a mother whom I am very close with, and two brothers (20, still lives at home, and 30, whom I am also very close with). I see him every other weekend for visitation, he knows I hate his guts but I try to control myself while over there. Right now he is taking my mother to court to try to get his money back (he says he over payed in child support but he didn't, it's been stretched out for YEARS, it's been horrendous and we're very tight on money). It's gotten to the point where I'm out having fun and these flashbacks or whatever they are just come into action and I have to leave the room to get a hold of myself. I am very mature and I already have a job, and I'm getting into college, my life is actually really great right now. Except for him. So here's my problem, during the day, I have INTENSE day dreams, it's weird, I realize I'm in them but it's so intense I just go along with it for some reason, it's gone on for about a few months now, increasing in severity. And at night I dream about it. It's almost always the same thing, he tries to take my girlfriend away from me, I never see him hurt her, just grab her and start to leave, but I know he's going to in the dream. And I can never stop him, although in the day dreams I usually end up getting her to safety. If you need more information just ask I'll but up for a while. Thank you so much in advance.

[Derrick]

Also, a lot of the times I do fight him, throw a few hard punches but he's a big guy and always gets away. I know part of this stems from my insecurity, I am pretty skinny and I worry sometimes because I can't really protect my girlfriend against some muscular guy, but that's only part of it.