In confirming the long-ago break-up, Lange's publicist declined to give a reason for the split or why it wasn't reported until now, People.com reported.
"They both are pursuing independent lives," an unnamed source close to the former couple told People.com.
Lange and Shepard, who had been together since 1982, have two adult children together.
Lange was nominated for a Golden Globe Award last week for her work on the TV drama "American Horror Story."
2014: The Year in Music [PHOTOS]