Yes. The term "sister-in-law" is used for two types of relationships:
Some languages may have some different terms for these two cases, but in English they're both "sister-in-law".
sisters in law
She is your sister-in-law.
I cannot see why not. There is no blood relationship between you and your sisters ex-husband.
sister in law
Brother-in-law.
Your sister-in-law.
brother-in-law
your brother-in-law :)
Mum's sisters husband is Masar Ji in Punjabi
Sisters of Saint Martha was created in 1900.
Not if he is still married to your sister.
Your niece in law.