Today the word mistress has a negative connotation and is used to refer to an adulterous woman. What did mistress mean as used in Shakespeare's "Sonnet 130"?

The word mistress during the Elizabethan era which was the time when Shakespeare wrote his plays had a very different meaning from the one we know nowadays.

A mistress was a high society woman, while people used to call master the men they also used to call mistress the women, so in this sonnet, he talks about his loved one as a woman with class and grace not a woman with a dubious reputation as we would think at first.