Dear Abby: Sister-in-law is burdened by knowledge of man's philandering

RO-51

DEAR ABBY: My husband works out of town with his brother, who is married. While I'm not close to my sister-in-law, I like her just fine.

My problem is, my husband keeps sharing with me that his brother is unfaithful while he travels, and I have actually overheard him on a call with my husband trying to show my husband nude pictures of other women. I cannot express how much this boils my blood. It's not only from the perspective of someone who has been cheated on before (not by my husband), but also that his brother's bragging with photos shows he doesn't respect ANY marriage or relationship.

I feel stuck with deciding whether I should share this information with my sister-in-law, or if it would be overstepping some kind of boundary where it's not my business.