It's one of the most painful conversations parents can have with their kids -- but Heidi Klum and Seal have broken the news of their separation to to their little ones.

In a pre-taped interview airing on Friday's Access Hollywood Live, Seal, 48, told Billy Bush that he and Klum, 38, have broached the sad subject with daughters Leni, 7, and Lou, 2, and sons Henry, 6 and Johan, 5.

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"Just explaining to them that things will be different, you know, without going into too much detail," the "Kiss from a Rose" singer said. "But a lot of things won't change."

The singer and the supermodel/TV hostess shocked fans worldwide when they announced their separation Monday after seven years of marriage.

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"The main thing," Seal continued, "is to make sure that they feel that they're loved, make sure that they understand that their parents love each other, make sure that they understand if there are any changes, it is absolutely nothing to do with them."

Indeed, a source tells the new Us Weekly that the superstar couple's adorable kids "are upset" by the news, but their welfare "will always come first" for both Seal and Klum. To that end, Seal will keep a home base in Los Angeles to minimize disruption when he isn't overseas.

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Seal added to Bush that the split "won't change the amount of time…that we spend with them."

What went wrong? Explains one insider: "They were the kind of couple who could have a huge fight over an order at Nobu."

And, indeed, co-parenting amid the busy couple's schedules -- Klum's multiple TV projects, Seal's touring -- was one of the many factors that led to their estrangement.

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"It's hard to make a marriage work when one parent is with the kids most of the time. They always took turns and it led to separate lives."

For more on the shocking split -- career tensions, Seal's moodiness and the final, fraught family trip to Aspen -- pick up the new Us Weekly, on stands Friday.

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