Question: is my brothers wife my husbands sister in law

Answer: Yes, One's sibling-in-law is one's spouse's sibling, or one's sibling's spouse. By gender, this is specified as brother-in-law for one's spouse's brother, one's sibling's husband, or one's spouse's sibling's husband, and sister-in-law for the one's spouse's sister, one's sibling's wife, or one's spouse's sibling's wife.