Jessica Simpson: Jealous of Carrie Underwood!

Although the two are now back together for “on trial basis,” a friend told In Touch about Jessica’s supposedly raging jealousy issues.

“Jessica can be so insecure when she is with Tony, and it only gets worse when he is around other women,” said the friend.

The pal says any female competition is bound to upset Jessica, but the subject of Tony’s ex, Carrie Underwood, really riles her.

“(Jessica) is really upset that (Tony Romo) is still communicating with Carrie,” the source told the celebrity news magazine.

Apparently, the Dallas Cowboys quarterback frequently contacts the country star via e-mail and text, even though he knows it bothers Jess.

“She had specifically asked Tony to stop,” the insider added.

And “things got worse for Jessica” when Carrie broke up with Gossip Girl star Chace Crawford back in March, according to the friend.

That’s when Jessica allegedly began to fear Carrie really could win Tony back:

“Jessica has to tone down how jealous she gets over things like this,” the friend adds. “It took a toll on their relationship.”

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