Last Ex to Brooklyn is the second episode of the sixth season and 118th overall.
Leo invites over her ex-girlfriend Diane for dinner; Grace invites Will, Jack and Karen. Things get painfully awkward for Grace when she learns that Diane and Will already know each other.
Grace and Leo host a dinner party to which his ex-girlfriend Diane is also invited. Diane, who is a writer for Vogue finds herself a new friend in Grace even giving her an Hermès Birkin bag.
Things turn difficult when Will, Jack, and Karen arrive and they all find out that Diane is the girl Will slept with during college, right after he broke up with Grace. This knowledge of their past drives Grace jealous, thinking that the woman Will slept with is "totally different than [her]", i.e. ugly. Leo then becomes indignant that his wife seems more jealous of Will and Diane considering he had an actual relationship with Diane.
While having dinner, things get even more tense especially after Karen asks Diane who was better in bed and she answers that Will was better, and that it was the only time she ever had an orgasm in her life.