Here's what OP should do:
1. Share this story to as many people as you can. From friends, to relatives, even neighbors. Show no fear. Write it down then mail them how much you hate your family
2. Share the story to the internet and make sure to dox your family as clearly as possible.
3. Print a copy of your letter and keep it under your clothes then jump off a building in a rush hour.

It does not matter whether you live or die. After this, your entire family and gf shall face the wrath of the public and they will regret ever messing with you.
You may go to hell but it is still better than living with these monsters.