Jessica Simpson can’t believe her former beau has moved on so quickly after their breakup.

The ‘With You’ singer was dumped by American football star Tony Romo in July. He is now rumored to be dating 22-year-old Candice Crawford, younger sister of Chace Crawford.

A source said: “She can’t believe it. She doesn’t want Tony back, but no one wants to see that their ex has moved on with a hot, younger girl.

“This couldn’t have come at a worse time for Jessica. It’s opened up a lot of old wounds. She’s pretty insecure about herself.”

Candice bears a striking resemblance to 29-year-old Jessica and the blonde beauty is trying to keep herself busy with work to get over her upset.

A friend said: “Jessica is unlucky in love and that’s her downfall.

“She’s buried herself in work and trying not to focus on the break-up with Tony.”