may be putting on a brave face – she's spent the past week shopping and partying with friends – but a source tells PEOPLE the heiress is hugely distressed about her impending jail time.
"Paris hasn't been eating at all and her parents and friends are beyond worried about her," the source says. "She breaks down crying a lot because she just can't deal with the reality and the pressure of everything that is happening."
Hilton, 26, was sentenced to 45 days in jail
for violating probation by driving with a suspended license, and a police rep recently said she will serve at least 23 days
of that sentence.
Hilton had said in a statement shortly after her sentencing: "I am ready to face the consequences of violating probation," and that seems to be the case – she dropped her appeal
less than two weeks later.
But the fact is, "She's been having such a tough time with it all despite her going out with friends and going shopping," the source says. "She just does that to keep her mind off things and to try and stay as normal as possible right now."
Hilton has until June 5 to turn herself in to the Century Regional Detention Facility in Lynwood, Calif. A police spokesperson confirms that Hilton will be placed in "special needs housing," a section of the jail reserved for high-profile prisoners.
Until then, she's counting on her family to help get her through. "Her biggest support has been her family – her parents without a doubt," says the source. "She talks to them a million times a day and they are doing everything they can to make sure that she comes out of this okay."
Some others, however, have not been as helpful. "As for her friends, that's been another spot of stress for Paris," the source says. "She really can't take how most people around her have scattered and distanced themselves."
Reporting by JENNIFER GARCIA