My sister in law constantly attacking my brother verbally about EVERYTHING about each of our family members.?

[yago]

we 2 sisters live abroad and my brother and and his wife live with my parents.my parents are very nice and polite and submissive with their daughter in law.my sister in law is very arrogant and dominating ,they got married last dec 2011. my brother is basically very calm,quiet and nice person. he emailed me today and asking me what he could do.my brother said he can't tolerate anymore when she says bad words about us. what suggestion should i give my brother?

[tredway]

Tell your brother to use his sack