McGregor, 46, filed the documents in Los Angeles County Superior Court, asking for joint custody of the three minor children he shared with Eve Mavrakis, his wife of 22 years.
Mavrakis asked the judge for sole physical custody with McGregor having visitation.
He told the judge he would be willing to pay spousal support.
Their date of separation was listed as May 28, 2017. That was the same month that his girlfriend Winsted split from her husband, Riley Sterns.
A heartbroken Mavrakis commented about the spilt when an Instagram user wrote to her: “I can’t believe Ewan would end things with u for that cheap whore! U are so much better than him!!!! Take him for every penny u can!!!!”
Mavrakis responded simply, “What can I do?”
McGregor and Winsted attended the Golden Globes, where he thanked both his wife and his co-star in his acceptance speech for Best Actor in a Miniseries.
“I want to take a moment to just say thank you to Eve, who always stood by me for 22 years,” he said. “And our four children Clara, Esther, Jamyan and Anouk.”
He then shockingly thanked his girlfriend. “And there wouldn’t have been any Ray without Mary Elizabeth Winstead.’
His 15-year-old daughter Esther wrote a song about her parents’ painful split that included the lyrics: “'I read some dumb s**t that I found online... Seeing those pictures... They’re making me cry'.”
The couple were caught kissing each other outside a London pub in October.
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