They were costars on the romantic, early '70s sitcom Bridget Loves Birney, man and wife from 1974 to 1989, and they had three children together.
But Baxter, 63, who came out as a lesbian in 2009, says her relationship with Birney, 71, was far stormier than it appeared.
In a new memoir, Untied, the actress says that Birney struck her on more than one occasion. (On Tuesday's Today show, it was said Birney has denied the accusation.) Recalling one incident, Baxter writes: "It was so sudden and unexpected, I couldn't tell you which hand hit me, or even how hard. I do recall thinking, 'I'd better not get up because he's going to hit me again.' "
The Family Ties star also writes that she coped, in part, by drinking heavily. She has been sober since 1990.