Your sister seems very insecure with herself & has low self esteem if she's putting up with this nonsense... was she always this way, or did his emotional abuse have the desired effect he intended?
She needs to be reminded of what an incredible catch she is.
He may have intentionally driven down her self esteem so she doesn't ever leave him, because he knows what a great catch she is (insecure men will always say things like "look at you, no guy will ever want you again looking like that" or "You'll be single forever because no guy wants to raise another guy's kid").
It's either that or he's just an asshole, period.
I love the mentality of the guy who thinks that calling his wife fat or moo'ing when she eats is going to motivate her to go to the gym & she'll think "I'll show him!"... but in reality, all it makes the wife do is eat more from pain, stress & depression from the emotional abuse.
Your BIL sounds like a total douche & if I were you, I'd hire some big ass dude to threaten him & scare the absolute living shit out of him, lol.
Guys like him need to be knocked down a few notches.
