You should call her sister-in-law, or aunt. Generally speaking, after a husband and wife get married, it is the same for them to address each other's relatives, and they only choose their names or addresses according to their age or seniority.

Husband calls his wife's brother "brother" orally and face to face, which is called by his wife's name. The person or address written is called "brother-in-law" and "brother-in-law".