Good grief. I could hear 'Deliverance' banjos playing as I read of your family. Look out for yourself. Study by all means.. the bible. Learn the exquisite value of your silence around them. Be a 'model' son do the dishes, mow the lawns etc. Are you at school? make the very most of it to get the best grades you can. agree with all they say or deflect. ie 'I have assignments' to do for next week.'
Your sisters attack is telling. She is young no doubt and jw kids are in my long experience at least two years behind their 'worldly' peers in social maturity so when she gets her first serious attack of the hots she will give your parents so much to deal with they will vector their guns off you giving you breathing space.
As Scratchme 1010 just said, "Some family members just don't drop it, so avoid that situation; it's not going to bear anything positive."
Do you have a job a trade or a career you would like to do? Aim for it now, seek information on it..now. I have utmost empathy for you pm me as you will.