"Daisy was her baby," one of them tells PEOPLE. "It's going to put her into a tailspin. It will put her into the worst place ever."
But another source close to the actress says she's coping better than her friends may realize.
"She's really upset, but she's not spiraling out of control by any means," this source says. "She'll get through this but it is like losing a family member. She's focusing on work and spending time with her family and friends."
Daisy was snatched away by a coyote before Simpson's very eyes in Los Angeles last week, and, despite Simpson's refusal to quit searching and offer of a reward, no sign has been seen of the caramel-colored dog. She was given the dog by [her] then-husband Nick Lachey in 2004, and Jessica and Daisy became inseparable.
"She won't leave her parents' house," a source says.
"Whenever things went wrong for Jessica, she reached for Daisy," another source, a friend, says. "Daisy was her security blanket. When people let her down, she always had Daisy."
On Sept. 19, her stylist pal Ken Paves convinced Simpson to finally leave her parents' house. They went to Vino in Encino, Calif., for an attempt to perk her up.
"Jessica seemed okay, but wasn't smiling much," an onlooker says. "The wine made her relax a bit, but it was still obvious that she was having a devastating week."
Unconditional LoveDaisy was perhaps one of the most pampered pets in Hollywood. Simpson fed Daisy steak, not dog food, and referred to herself as "Daisy's Mommy." When leaving the house, Simpson left on the air-conditioning for her dog; and when Daisy was sick, Simpson refused visitors so that they wouldn't wake Daisy. She threw Daisy birthday parties, and when she talked about having a "girls' night in" with a video, she was talking about herself and Daisy.
"Jessica has a very small inner circle," the friend said. "But she always had Daisy. Daisy gave her unconditional love."
And, unlike some of the men in her life, the friend added, "Daisy never betrayed her. Daisy was always there for her. This is serious. Jessica’s heart is broken."
Spoke on Phone
Courtesy Jessica Simpson
"Daisy ran the household," the friend said. "If Daisy didn’t like you, you were gone. Sometimes if her regular hair and makeup people weren’t available and Jessica had a sit-in, if Daisy didn’t like them, they wouldn’t be back. Daisy [ruled] the roost."
When Simpson was having relationship problems, "she would cry herself to sleep at night, using Daisy as a pillow."
It won't be easy to find a replacement, another friend said.
Needy and Clingy"Jessica is very needy. She is very clingy," the friend said. "She is so sweet, but sometimes because of that she's hard to be around. It's not always easy. She hates to be alone. That's what happened with [ex-boyfriend and Dallas Cowboys quarterback] Tony [Romo]. Jessica smothers people. She doesn't really have any hobbies. Daisy was exactly what Jessica needed."
All of the sources agreed on one point: It's been a tough year for Jessica Simpson.
"I want her to catch a break," the first friend said.