Just like to say....?

Sorry bout what the shia dude did to u, im shia, and it sounds like he was a jerk, anyways, ur dad isnt muslim is he??, cuz if he isnt theres not much that you can religiously do, if he is, just call in an actual alim, just destroy his reputation, show him a couple of hadiths, bring him the quran, if al else fails, take in some of ur siblings, and have everyone distance them from ur dad.