"Sam's family has made her swear that it's really over," a friend of Lohan and Ronson's tells PEOPLE. "They are giving her all the support they can to keep her away from Lindsay."
Adds another source close to Ronson: "Lindsay is going to try and twist the situation in her favor, but Sam clearly left her, not the other way around."
Lohan herself spoke out on Monday telling E! news, "We are taking a brief break so I can focus on myself."
Meanwhile, Lohan has reportedly written several messages on her private Twitter page alleging Ronson's infidelity and drug use led to their breakup. In one message, the actress wrote, "You broke my heart. Now go away. I loved you."
Locked OutThe on-again off-again pair have not been spotted publicly together in recent days, while Lohan has been a fixture on the L.A. scene, stopping into Chateau Marmont with her sister Ali on April 1, and even jumping on stage to sing along with Lily Allen during the British pop star's concert the following night at the Wiltern.
Over the weekend, Ronson changed the locks on her house, a friend of the pair confirms. "Sam changed the locks on her house," the source tells PEOPLE. "Lindsay moved her stuff out as much as she could. She's basically totally out of the house as far as her stuff and she's not living there anymore."
Adds the source: "Lindsay was pretty devastated."
Not Invited to the PartyThis weekend, Lohan attempted to get into the "I Heart Ronson" bash at Bar Marmont in West Hollywood – an event celebrating Charlotte Ronson's clothing line and deejayed by Samantha Ronson.
"Lindsay was banned from the event and was trying to enter from all ends," says a source. "Sam did not want her there."
The next night, Lohan hit up other hot spots including the Hollywood Roosevelt Hotel. According to a paparazzo, who spotted the star at McDonalds later in the night, "Lindsay kept hiding her face in her hands … One second she would scream that we were scaring her and the next she started rambling about how much she loves Samantha."
Reporting by PERNILLA CEDENHEIM