Care and Feeding: My older sister is throwing a tantrum over something that shouldn’t even be an issue

My older sister, " Evelyn ," is throwing a tantrum over something that shouldn’t even be an issue: She used to date my fiancé, " Kenneth ," but it was when they were in seventh grade.

When I told Evelyn , she freaked out. She demanded that I break up with Kenneth immediately. Now that we are getting married, she is accusing me of “betraying” her and threatening to boycott the wedding.