PRETTY Seattle native CATHERINE GIUDICI battled hotties galore to nab a mar­riage proposal – from “Bachelor” Sean Lowe, but she can’t let down her guard just yet!

Insiders say she’s steaming that her handsome honey has been paired with blonde bombshell Peta Murgatroyd on the new season of “Dancing with the Stars”!

Although The “Bachelor” fi­nale just aired on March 11, Sean actually proposed to Catherine in November, when the ABC show was taped at the Pa Sak Tong Villa in Northern Thai­land.

“Catherine thought all her romantic problems would be solved once she received the final rose from Sean,” said a source. “But then the network threw her a curve when she was told that Sean was going to dance with Peta.

“She’s furious! The last thing she wants is Peta cozy­ing up to her man.”

Regular followers of “DWTS” will have noticed that there were only 11 couples instead of the usual 12 an­nounced at the cast reveal on “Good Morning America” in February. But the network con­firmed that Sean and Peta would fill that last spot the day after the “Bachelor” finale aired.

“Catherine is fit to be tied,” said the source. “The last person she wants her fiance to be doing a pas­sionate tango with is Peta!”

Peta is just coming out of a   bitter breakup with ladies’ man Maksim Chmerkovs­kiy, and the source says she’s now looking for a new man.

“Catherine’s worried sick that Peta might try to waltz her way into Sean’s heart!”

Peta, 26, and Maks, 33, split in February after 10 months of dating.

AS THE ENQUIRER re­ported in early August, the steamy romance blindsid­ed Peta’s former boyfriend and fellow Aussie Damian Whitewood. Peta and Da­mian, a pro dancer who appeared on Season 10 of the hit dance contest, had been together for five years before she coldly dumped him for Maks.

“Because of Peta’s past, Catherine’s afraid that nothing would stop her from trying to worm her way into Sean’s heart,” added the source. “That’s brought out the green-eyed monster in her.”