It will keep happening until you fight back. Establish your ground and fight back.
Agree! The guy's family walks all over him most likely because they can see he's weak. Otherwise.......I've seen parents back off when their sons develop a backbone and take some action.
I feel DISGUSTED that the guy's sister believes she can beat up her bhabi. WTH? What is she? A pehlwan? That's crossing the line. And at this point.....it would require miraculous self-control for me...NOT to b*tch-slap the heifer.