Kelly Clarkson & Brandon Blackstock's 'Tense' Legal Battle Ruining Christmas

It's beginning to look a lot like an all-out war! Kelly Clarkson and her estranged husband, Brandon Blackstock, are bracing for a less-than-stellar holiday season.

After Starstruck Management Group, the company Blackstock, 43, runs with his dad Narvel, sued Clarkson — a longtime client — for $1.4 million in unpaid commissions, the pop star, 38, countersued, deeming the request unlawful and demanding $1.9 million in prior commissions be returned.

"Things were already pretty tense given their divorce and custody issues," says a source, "so this just makes it harder to be civil."

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Worse, their once-optimistic hopes for a cordial holiday season with their two young kids have been effectively dashed. "The original plan was to try to co-parent amicably and even spend Thanksgiving and Christmas Day together," says the source. "But they're at each other's throats — so a truce before the festivities begin is looking unlikely." So much for that yuletide cheer.

Clarkson filed for divorce from Blackstock earlier this year in June after seven years of marriage. "Let's just get this out of the way. 2020 has been a dumpster fire. Yep, just all the words I can't say on this show, just piled together, and it's on fire. That's really what it feels like," she said on her talk show in September.

However, Clarkson looks ready to start a new chapter in her life. As OK! previously reported, the "Since U Been Gone" songstress has her eyes on her collaborator for "Under the Mistletoe" — 34-year-old Brett Eldredge.

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“They spent lots of time together in the studio and on the phone, and really bonded while they were cutting this sexy song,” the insider spilled, adding that “there was some flirting going on.”

“Kelly’s swooning over Brett’s handsome face and gentlemanly manners. On the one hand, it’s just what she needs for her confidence,” the source said. “But there’s genuine concern because Brett’s a real lady-killer who could leave her brokenhearted.”