Aidan's ex wife is played by Rosemarie DeWitt. She is married to Ron Livingston who played Jack Berger in SATC as the one who broke up with Carrie by a Post it
Rosemarie DeWitt also appeared in an episode of Sex and the City as Fern (season 6, episode 6).
Elaine Bromka also appeared in an episode of Sex and the City as Dr Finch (season 2, episode 11).