Aunt
your moms sisters husbands bests friends daughters teachers students aunt
Yes, it should be, it is not considered incest because it is not by blood. You are marrying your aunt's HUSBAND'S daughter.
I would say aunt in law. If I'm reading this right, you were introduced to your mother.
John's sister's husbands mother in law is John's Mother. He went to the movies with his aunt.
Technnically, she is not related as you do not share a common ancestor. She would refer to you as Aunt and she is your niece. Whether he is your first, second or fifth husband, his niece is your niece while you are married to him.
Aunt's
husbands' ex: All of the women have their husbands' money.
The possessive form of the plural noun husbands is husbands'.Example: Both of her late husbands' estates were considerable.
Tom Sawyer's aunt was Aunt Polly.
Great aunt.
Your great aunt.
Your mother would have been your aunt's sister, not her cousin. Nearest relatives are usually defined in the law of the state where you live. Your aunt's nearest relative would have been her husband. If she had no living husband (ex-husbands don't count) then her children and her siblings would be her nearest relatives. After that, nephews and nieces, then cousins. Unless named as such in a will, in-laws are unlikely to be in the chain of next-of-kin themselves, but may be married to someone who is.