I've been kicked out.

I pretty much went a little nuts today, could it be because I changed my meds two weeks ago? Maybe I am having Zoloft withdrawal symptoms?
slight possibility...more likely an excuse for your behavior
I went on Efexor XR two weeks ago, 75mg.

I basically got frustrated and yelled a lot after continuing an argument that's been going on the last week. (Read "I guess I'm moving out . . ." for more information)

Then my dad got involved and I hit him.
Then he said to call the cops and I told them don't bother, cos i'm leaving.
Then I got into a tangle with him again, shoving him around a lot.
Then I hit him over the head as I left, throwing him to the ground.
Elder Abuse...in this state, you can be arrested for these actions.
I hope your father was not seriously injured. Shoving him around, Hitting Him Over The Head, then throwing him to the ground? Takes a real man to do that...I'm glad you didn't kill him.
You think living there was tough? Try Jail
His heart must be broken...
oh yeah, I know the "it takes two." you are younger and most likely stronger. you knew the situation was escalating and should have left before it reached this point.
I sincerely hope your father has no lasting Physical effects from your abuse. His mental health is another story...
While I appreciate your honesty in posting this, there is no justification in turning to violence to handle this ongoing problem.
Perhaps you need to seek help with your anger issues and lack of impulse control.
I have no sympathy with an abuser of any kind. Seek help before this becomes more dangerous. To your parents, to you.
My biggest regret is that my two nephews were present, the older one started crying.
They didn't see most of it, just the shouting.
"Just the shouting" I'm glad you have regret for this at least.

"most of it" means they still saw something...yeah, good memory for them.
this bit of justification just doesn't float
In a way this is a good thing because now I am forced to move out of home and get a job.
Yep and about time
From crisis comes opportunity right?
too bad it took something like this to get you off your arse
I'll make it up to my nephew tomorrow, if that's possible.
two nephews, right? both were equally affected by this episode.
and can you do that without blaming your father? how about a simple, "I'm sorry you saw/heard us fighting." Acknowledge their fears and reassure them that everything will be all right. Don't use them/get them on your side...might make you feel better, but it sure as heck will hurt them.

Yeah, seize the opportunity to do what you can to make your own home, get counseling for your problems--facing issues with either of your parents--accepting responsibility for your actions...
and making amends whenever possible and without excuses or accusations
Start living a life that will have more stability and self esteem, and you will have a measure of peace.

Hopefully, your parents will be able to move on with their lives and find their peace again.

Recovery works both ways...theirs and yours.