She is married to Jackson Douglas and has two children.
In the early 1990s, Borstein broke into the television business as a script writer for the cartoon series Pinky and the Brain. She had also written scripts and voiced other cartoon series when she joined the Fox late-night sketch comedy show MADtv. There, she was best known for her Mrs. Swan character. The character had a cameo during the episode "Don't Make Me Over". Borstein left MADtv in the 2001-2002 season. Borstein has also appeared on the TV show Friends and was also the voice of Power Rangers Zeo villain Queen Machina. She also briefly co-hosted the Celebrity Blackjack series for GSN.
She co-wrote It Takes a Village Idiot, and I Married One with Cherry Chevapravatdumrong. For the episode on which the book is based, she is credited as a.bo. She co-wrote the special Family Guy Presents: Seth & Alex's Almost Live Comedy Show, which she also hosted and performed. She wrote "Deep Throats" and the second segment of Stewie Griffin: The Untold Story, "Bango Was His Name Oh", on her own, while she and Mike Henry co-wrote "A Fish out of Water".