Sometimes the best thing to do after a bad breakup is just cry with your girlfriends -- and it looks like that post-split remedy holds true in the pop star sisterhood as well. Since her breakup from Russell Brand, Katy Perry has found comfort and a sympathetic ear from best bud Rihanna.

The newly-single singer is doing her best to carry on with her commitments despite being blind-sighted by the divorce filing from her now-estranged husband. She is set to make her first U.S. public appearance since the split when she co-hosts the GiveLove charity event in Las Vegas tonight (Jan. 27), and we're sure girlfriend could use a little support. Enter Rihanna!According to a Hollywood Life source, "Katy's friends are doing everything they can to help keep her happy and just be there to listen to her," and there has been one pal in particular who is showing Katy some extra love. "Rihanna has been unbelievable and checks up on her every day and even invited her on a trip," the insider revealed.

In an earlier story in The Sun, another source reported, "Katy is hardly speaking to anyone right now, but she called Rihanna as soon as she heard Russell was filing for divorce. When Katy told her the news, she suggested flying down to Barbados to stay with her and her family." The Hollywood Life insider also suggested that Ri may fly to be by Katy's side at the 1 Oak-hosted charity event tonight. "Katy even asked Rihanna to meet her in Vegas and be there with her."

It's a good thing Katy has friends like Rihanna checking in on her. Apparently the split has caused the already slim star to start skipping meals. "Katy has really lost her appetite" the insider revealed. "She is doing her best to remain upbeat while at work but she is deeply hurt."