Moakler rushed to Barker's side immediately after learning about the crash, which took place in Columbia, S.C., around midnight Friday.
"She's there trying to lift his spirits," a source close to Moakler tells PEOPLE. "She's there for him and will be there for him as long as it takes. She loves him."
The source went on to say about Moakler, "When she got the call, she was in shock. She was very upset. It was devastating for her. But she knew she had to keep it together for Travis, her kids and her family."
'He Was Part of the Family'Barker's assistant, Chris Baker, was among the passengers who perished in the crash. "They lost Chris, Travis's best friend," says the source. "He was part of the family. They are really upset about his death."
Ralph Notaro / Splash News Online
In all, four were killed. In addition to Barker there were pilot Sarah Lemmon, 31, of Anaheim Hills, Calif.; co-pilot James Bland, 52, of Carlsbad, Calif.; security guard Charles Still, 25, of Los Angeles; and Barker's assistant Chris Baker, 29, also of Los Angeles.
Moakler released a statement through her publicist Monday, saying, "There are not enough words to express how thankful we are for the outpouring of love and support we have received during this very difficult time. We can only ask for prayers as we heal and mourn the loss of our dear friends who we considered part of our family. Our lives will be changed forever."
Married from 2004 until earlier this year, the Dancing with the Stars alum 33, and Barker still remain close, says the source. They have two children: son Landon, 4, and daughter Alabama, 2.
2004: Inside Travis & Shanna's gothic wedding
2005: Meet the Barkers!
2006: Shanna opens up about her bitter breakup with Travis
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