Billy Joel was still dating Elle Macpherson when he met Christie Brinkley

She told Stellar Magazine: "We were at his apartment and he said, 'I'm going to call Elle because I've been out with her a couple of times and I want to let her know that now I want to be exclusive with you.'"

Billy ended things with Elle, 61, before he and Christie went on to date and tie the knot.

They were married for nine years before divorcing in 1994.

Billy and Christie have remained close friends and she revealed the whole family is supporting him though his recent battle with a rare condition called Normal Pressure Hydrocephalus (NPH), which is caused by a build-up of fluid in the brain.

She said: "Alexa just had a long conversation with him and she said he sounded good. We're all just cheering him on."

Christie previously called Billy her soulmate but admitted his addiction issues ruined their marriage.

She told Page Six: "If there wasn't that issue, I do think that we were probably really soulmates. It was an amazing time of my life.

"I had so much fun. We were such nomads, gypsies - just between his job and mine, we were seeing the world. It was wonderful, really wonderful."

Billy recently axed all of his tour dates - including 17 dates in North America and England - amid his diagnosis.

Announcing the news on social media, a statement from Joel's team read: "Billy Joel has announced that he will be cancelling all scheduled concerts following a recent diagnosis of Normal Pressure Hydrocephalus (NPH).

This condition has been exacerbated by recent concert performances, leading to problems with hearing, vision and balance.

"Under his doctor's instructions, Billy is undergoing physical therapy and has been advised to refrain from performing during this recovery period. Billy is thankful for the excellent care he is receiving and is fully committed to prioritising his health.

"He is grateful for the support from fans during this time and looks forward to the day when he can once again take the stage."