The fashion designer, who divorced the Alfie star in 2003, has three children with the actor - Rafferty, 13, Iris, nine, and seven-year-old Rudy.
Law recently became a dad again, fathering a baby girl with American model Samantha Burke following a fling earlier this year (09) - and internet gossips suggested the news had infuriated Frost because of the implications for her own young children.
But Frost is adamant she will always stand by her ex - no matter what.
She tells Britain's Grazia magazine, "We're continuing to have a very close relationship and I'm here to support him as a friend. That won't stop. He's a wonderful person and I'll stand by him forever. For all the silliness and difficulties, we've always really cared for each other and we're both a hundred per cent committed to the kids and doing the right thing by them. Everything's fine."