Jude Law and Sienna Miller have reportedly vowed to take things "incredibly slowly" after deciding to rekindle their romance.
Last week, the pair sparked rumours that they were back together when they were spotted enjoying a night out in New York.
According to the Daily Mail, Law has now confirmed the news in private discussions with former partner Sadie Frost, with whom he has three children.
A source said: "Jude has told his ex-wife Sadie that Sienna is back in his life. Sadie is calm about it - her only concern, as ever, is their children. She doesn't want any more shocks for them."
The insider added: "Jude and Sienna are taking things incredibly slowly, but they are getting back together again. Both are very wary of relationships."
Law split from Miller in 2006 after confessing that he had been unfaithful.
In September this year, the actor became a father for the fourth time when ex-lover Samantha Burke gave birth to a baby girl.