Nighy splits from long-term partner
The actress has reportedly dumped Nighy and moved out of their London home.
The couple said in a statement: "Bill and Diana separated amicably. They remain great friends."
A source told the News Of The World: "This is a devastating split. Everyone thought their relationship was rock solid, but Diana wants nothing more to do with him."
The pair never married, but Nighy, 58, referred to Quick as his wife and credited her with helping him overcome his alcohol addiction. Meanwhile, Quick, 61, called him POSSLQ - Person Of The Opposite Sex Sharing Living Quarters.
The couple, who have a 24-year-old daughter Mary, met in 1981 while starring in a play at the National Theatre.
They are thought to have split as a result of Nighy's hectic schedule.